SEARCH

SEARCH BY CITATION

Keywords:

  • Chasmatopora;
  • Phylloporina;
  • Phylloporinina;
  • Bryozoa;
  • taxonomy

Abstract

  1. Top of page
  2. Abstract
  3. The problem
  4. Systematic palaeontology
  5. Discussion
  6. References

Abstract:  The family Phylloporinidae was introduced in the late 19th century to accommodate a small number of Palaeozoic bryozoan genera characterized by irregularly fenestrated colonies generated by anastomosis of unilaminate branches. Among the first named of these genera were Chasmatopora Eichwald, 1855 and Phylloporina Ulrich in Foerste, 1887. The two names have been variously in fashion, and there has been confusion about whether they are subjective synonyms or are distinct genera. This taxonomic confusion has been due in large part to whether the single species (Retepora angulata Hall, 1847) assigned to Phylloporina in Foerste (1887) or the species that Ulrich intended (Retepora trentonensis Nicholson, 1875) is the type species and also because of lack of sufficient information about Foerste’s material to characterize it well. We here redescribe the pertinent species, erect the new species Chasmatopora foerstei for the species that Foerste incorrectly assigned to Phylloporina angulata (Hall), and suggest that Retepora trentonensis Nicholson be retained as type species of Phylloporina based on prevailing usage, until the issue is settled by the International Commission on Zoological Nomenclature.

D uring approximately the first half of the 19th century, various irregularly fenestrated Palaeozoic bryozoans were named as new species of Retepora, an extant genus erected by Lamarck (1801, p. 374). Harmer (1933, p. 618) noted that ‘M[illepora]. cellulosa L., 1767, must be [the type species] of Retepora’ and (p. 616) that ‘the diagnosis is applicable to practically all the species of Retepora auctt. and to certain Cyclostomes’. The diagnosis can be tied to a drawing of Mediterranean material in a mid-18th century monograph that is too generalized to be matched with any of several living reticulate bryozoan species that occur in the Mediterranean Sea (Harmer 1933). Retepora is no longer recognized by bryozoan taxonomists.

Realization that the Palaeozoic bryozoans originally described as species of Retepora needed to be reassigned resulted in the introduction of new generic names. The most important of these are ChasmatoporaEichwald, 1855 and Phylloporina Ulrich in Foerste, 1887, both of which are type genera for different families in the suborder Phylloporinina Lavrentjeva, 1979.

As indicated below, the type species of Phylloporina makes it a junior synonym of Chasmatopora, whereas the intended type species of Phylloporina would have established a distinctly different genus and would match the prevailing usage of the genus Phylloporina. The purpose of this article is to summarize the origins and histories of usage of the genera Chasmatopora and Phylloporina; to redescribe Retepora tenella Eichwald, 1840, R. trentonensis Nicholson, 1875, and R. angulataHall, 1852; to designate type specimens for the latter two species and to discuss the implications of retention of the type species of Phylloporina. Resolution of problems involved in the concept and status of Phylloporina is necessary before revision of the Fenestrata for the Treatise on invertebrate paleontology.

The problem

  1. Top of page
  2. Abstract
  3. The problem
  4. Systematic palaeontology
  5. Discussion
  6. References

The name Phylloporina first appeared in print in an article by A. F. Foerste as ‘Genus PHYLLOPORINA, Ulrich’ (1887, p. 150). Only one species, ‘Phylloporina angulata, Hall’ was mentioned in the article; it was described on pages 151 and 152 based on specimens from the Silurian Clinton Group at ‘Soldiers’ Home Quarries, Brown’s Quarry, Fair Haven, Todd’s Fork’, [Dayton], Ohio. Retepora angulataHall, 1852 (p. 49) as applied to Phylloporina by Foerste (1887, p. 151) is therefore by monotypy the type species of Phylloporina according to Article 68.3 of the International Code of Zoological Nomenclature. However, as indicated by Ross (1963, p. 593), ‘The taxonomic position of the specimens assigned by Foerste to P. angulata is not known’. Neither Foerste’s specimens nor Hall’s species have been redescribed, and the original descriptions and illustrations are inadequate to decide whether they are conspecific. Foerste (1887) had intended to illustrate Phylloporina angulata in accompanying plates, which were omitted when the article was published. Plates 15 and 16 were published the following year (1888, Bulletin of the Scientific Laboratories of Denison University, volume 3), but Plate 17 was never published. Unfortunately, the single enigmatic illustration of P. angulata on Plate 15 is a generalized drawing of the ‘small form for which the name P. [sic] Daytonensis was suggested by Hall and Whitfield’ (Foerste 1887, p. 174). Plate 17, which was to include drawings of the obverse and reverse sides as well as a tangential section (Foerste 1887, p. 175), never appeared.

Apparently, E. O. Ulrich shared with Foerste information about his intended new genus Phylloporina, which was part of his large manuscript, Palaeozoic Bryozoa. The article was to be published in the eighth and final volume of Geological Survey of Illinois organized by A. H. Worthen. In Worthen’s transmittal letter for volume 6, it is clear that funding for the Survey itself was exiguous and that support for publication of the volumes was intermittent, leading to delays of various lengths (transmittal letter cited in Kent 1982). Substantial problems plagued the production of volume 8, which does include the large bryozoan article by Ulrich (1890). The Illinois State legislature passed an Act in June 1885 for production of volume 8 within 2 years, but the volume did not go to the printer until early 1889, about a year after Worthen’s death, with a further exasperating delay of a year and a half before printing was accomplished (Lindahl 1890). Ulrich apparently expected a timely publication of the volume and gave access to the contents of his article not only to Foerste but also to at least one other. S. A. Miller’s North American Geology and Palaeontology appeared in 1889 and included all of Ulrich’s 1890 new bryozoan genera in his listing of taxa, and Ulrich himself listed the combination Phylloporina trentonensis (Nicholson) in an article that appeared a year earlier than the volume (Ulrich 1889).

Ulrich (1890, p. 399) not only listed ‘Phylloporina n. gen.’ but established ‘Family Phylloporinidae n. fam.’ based on it when volume 8 finally appeared. In that article, he designated ‘Types: Phylloporina trentonensis Nich. and P. asperato-striata Hall’ (Ulrich 1890, p. 399), illustrating both species in multiple thin section views. He later (Ulrich 1895, p. 208) listed only P. trentonensis as the type species.

Several species were listed as Phylloporina in A Synopsis of North American fossil Bryozoa (Nickles and Bassler 1900), but the only assessment of Chasmatopora Eichwald – cited as 1860 rather than the original 1855 article – was ‘This appears to be a Phylloporina’ (p. 55). A decade later, Bassler (1911, p. 169) had realized, given the precedence of Chasmatopora Eichwald, that Phylloporina needed to be considered as a junior synonym based on the information available. He noted (p. 169), however, that ‘As pointed out by Ulrich, several distinct types of structure are included in Phylloporina. It is therefore probable that with more study, both Phylloporina and Chasmatopora may be recognized’. Foerste (1919) apparently followed Bassler’s acceptance of Phylloporina as a junior synonym of Chasmatopora, including Chasmatopora angulata (Hall) in a taxonomic list, the same species that he had described in 1887 as Phylloporina angulata (Hall).

The first suggestion of particular differences between Chasmatopora and Phylloporina appears to have been given by Bekker (1921, p. 48)‘In the material that I have at my disposal, may be noticed two types. Seen in transverse sections one type has the zooecial tubes more or less regularly disposed on one side of the zoarial rounded branch; this type could include all species of the gen. Chasmatopora. The other type is with zooecial tubes irregularly disposed throughout the whole branch of zoarium. This type could include the species of the gen. Phylloporina Ulrich’.

In 1935, Bassler differentiated Phylloporina from Chasmatopora in the Fossilium Catalogus, but judged Chasmatopora to be a junior synonym of Subretepora d’Orbigny, 1849. However, the type species of Subretepora, Intricaria? reticulataHall, 1847, is unrecognizable from its original description, and the original specimens are not in any of the major repositories of James Hall’s specimens, i.e. New York State Museum, American Museum of Natural History, U.S. National Museum of Natural History, The Field Museum, and University of California Berkeley. At present, Subretepora is unrecognizable.

Between 1935 and 1960, there was instability in use of the name Chasmatopora. Nekhoroshev (1936) and Shulga-Nesterenko (1955) used Chasmatopora as a senior synonym of Phylloporina. In other publications, it was treated as a synonym either of Subretepora (Shulga-Nesterenko 1952; Bassler 1953) or of Phylloporina (Toots 1952; Männil 1958). There was no discussion of why precedence was given to one name or the other in these articles.

Chasmatopora and Phylloporina were treated as separate entities in the bryozoan volume of Osnovy paleontologii (Shulga-Nesterenko et al. 1960). Brief characterization of the two genera was based on external and internal features of the type species listed in the volume: Retepora tenella Eichwald for Chasmatopora and Retepora trentonensis Nicholson for Phylloporina. In the synopses, overall colony habit (narrow unilaminate, irregularly anastomosed branches in erect colonies) was given as similar, but a medial wall separating an even number of rows (usually two) per branch was noted as characteristic of Chasmatopora, and Phylloporina was described as having no medial wall and either an odd or even number of rows of zooecia. In that volume, there was no discussion of the history of tangled usage of the names Subretepora, Chasmatopora and Phylloporina. However, with characteristic verve, Nekhoroshev (1961), one of Shulga-Nesterenko’s co-authors for Osnovy paleontologii, discussed and gave his opinions on the main points of the history and applied the names Chasmatopora and Phylloporina to new species consistent with their characterization in Osnovy paleontologii. The characterizations given in the bryozoan volume of Osnovy paleontologii have been the foundation for common understanding of the two genera since its publication.

Systematic palaeontology

  1. Top of page
  2. Abstract
  3. The problem
  4. Systematic palaeontology
  5. Discussion
  6. References

Figured and cited specimens are housed in the American Museum of Natural History (AMNH); the Natural History Museum, London (NHM); the Palaeontological Institute, Moscow (PIN); Tartu University (TU) and the National Museum of Natural History, Washington (USNM).

Suborder PHYLLOPORININA Lavrentjeva, 1979 Family CHASMATOPORIDAE Shulga-Nesterenko, 1955 Genus CHASMATOPORA Eichwald, 1855

Type species. Retepora tenella Eichwald, 1840.

Chasmatopora tenella (Eichwald, 1840) Plate 1, figures 1–5

image

Figure EXPLANATION OF PLATE 1.   Figs 1–5. Chasmatopora tenella (Eichwald, 1840). 1, 2, NHM D 29831, H. Bekker Collection. 1, reverse surface locally weathered into exozone on opposite side of branches, ×5. 2, longitudinal striae on reverse surface of branches, ×15. Tarpsalu, Estonia, Kuckers C2, Kukruse Formation, Middle Ordovician. 3–5, neotype, PIN 3535/76. 3, tangential section (thin section b) cutting all levels from reverse surface to obverse surface, ×20. 4, tangential section (thin section a) through several zooecia in the obverse exozone and shallow endozone, ×100. 5, transverse section (thin section c) across a single branch with a very thick exozone of laminate skeleton, ×100. Palukula, Hiiumaa island, Estonia, Vormsi Stage, Upper Ordovician.

Download figure to PowerPoint

  • 1840aRetepora tenella Eichwald, p. 207.

  • 1840bRetepora tenella Eichwald, p. 219.

  • 1842Retepora tenella Eichwald, p. 47, pl. 1, fig. 7.

  • 1855 Chasmatopora (Retepora) tenella (Eichwald); Eichwald, p. 460.

  • 1860 Chasmatopora tenella (Eichwald); Eichwald, p. 371.

  • 1911 Chasmatopora tenella (Eichwald); Bassler, p. 169, Fig. 85.

  • 1985 Chasmatopora tenella (Eichwald); Lavrentjeva, p. 43, pl. 15, fig. 6a, b.

Type specimen.  Neotype (designated by Lavrentjeva 1985), PIN 3535/76, Vormsi Stage, Upper Ordovician, Palukula, Hiiumaa island, Estonia.

Additional material.  NHM D.29831, Kuckers C2, Kukruse Formation, Middle Ordovician, Tarpsalu, Estonia; H. Bekker Collection.

Earliest description.  ‘Der Korallenstock ist ästig, die Aestchen vereinigen sich unter einander und lassen grosse Maschen zwischen sich; die runden, nich vorspringenden, sondern eingesenkten Zellen sind als kleine Poren in ziemlich unregelmässigen Reihen nur auf einer Seite des Korallenstocks sichtbar, wärend die andere glatt oder gestreift erscheint’. (The zoarium is branched, the tiny branches united with one another and leaving large interstices between themselves; the round, nonextended, undoubtedly single-type cells are like small pores in moderately irregular rows visible only on one side of the zoarium, while the other is plain or striped.) (Eichwald 1855, p. 460).

Description.  Zoarial fragments generally planar, consisting of sinuous, bifurcating unilaminate branches anastomosed at irregularly spaced intervals, with a lagging branch commonly terminated and fused against the side of a leading branch. Branch width variable, high for fenestrate bryozoans. Obverse surface of branches with node-bearing median keel. Reverse surface of branches with uniformly spaced longitudinal striae. Four rows of autozooecia, two on either side of branch, with rounded, essentially circular autozooecial apertures, more closely spaced along central obverse rows than along lateral rows. Fenestrules variable in size and shape but typically highly elongate oval.

Branches with median granular near-planar wall extending along branch axial plane from reverse to obverse sides of endozone. Autozooecia budded at two levels from median wall, so that branches are bilaterally bilaminate.

In endozone, autozooecia elongate tubular, straight, extending obliquely disto-frontally at low oblique angle to branch axial plane; length about four to five times width; walls approximately 10 μm thick. Pronounced bend and slight constriction in autozooecial diameter by nominal superior hemiseptum at transition to exozone, where zooecia have diameter slightly increased over that of endozone and are separated by extrazooecial laminate wall (i.e. laminate skeleton outside the margins of the zooecia); axes in exozone curved such that axes are at high angle to branch surface; exozone relatively thick, up to more than 50 per cent total branch width in neotype. Diaphragms uncommon but isolated diaphragms locally present within endozone.

Mesozooecia and other heteromorphs apparently absent.

A thin, often poorly visible granular wall bounds the reverse surface of the endozone, with several thin, low, longitudinal ridges on the reverse side, covered by thick exozonal laminate skeleton; crests of the low longitudinal ridges each give rise to an outwardly proliferating set of small-scale folds extending through the reverse exozonal laminate skeleton along with abundant, very small microstyles, which are also present in laminate wall of the obverse side. One or more larger (5–10 μm diameter) microstyles around exozonal portions of zooecial tubes. In areas of very thick laminate skeleton, vesicles may be present locally, constricting fenestrule size.

Discussion. Lavrentjeva (1985) reported oval zooecial apertures, with minimum diameter of the ovals approximately equal to measurements reported here and length about 50 per cent greater. Where measurements of apertures (outer termini of distal tubes) are determined from an oblique view of the distal tube cross section, the long axis of the oval is dependent on the angle of the plane of the section with the axis of the tube rather than being a measure of the actual diameter of the tube. Our measurements were made from thin sections, so to measure the long axis would have been spurious.

According to Lavrentjeva (1985), peristomes around zooecial apertures are indistinct and are not greater than 20 μm in width. The narrow dark-textured rings bounding the cross section of each distal tube suggest intersection of wall laminae at high angles as would develop in narrow peristomes as she reported. She also reported that the keel nodes, presumably the granular cores of the nodes, are 30 μm in diameter with centres ranging from 0.37–0.50 mm apart.

Measurements. Table 1.

Table 1.   Zoarial and zooecial measurements (in mm) of Chasmatopora tenella in the Paleontological Institute, Moscow (PIN 3535/76), Chasmatopora foerstei in the National Museum of Natural History, Washington (USNM 84851, 528949 and 528950) and Chasmatopora? angulata in the American Museum of Natural History, New York (AMNH 30711 and 30712).
 ADASMASLBWBSFLFWSS
  1. AD, aperture diameter; ASM, center to center spacing of apertures in the two medial rows; ASL, center to center spacing of apertures in the two lateral rows; BW, branch width; BS, center to center branch spacing; FL, fenestrule length; FW, fenestrule width; SS, center to center distance between spines on obverse keel.

Chasmatopora tenella
 N121012107517?
 X0.0890.2060.3060.5101.0451.4590.483 
 SD0.0120.0200.0300.0690.0970.4100.139 
 Min0.0700.1890.2420.4020.8741.0960.289 
 Max0.1070.2530.3700.6261.1452.0610.714 
Chasmatopora foerstei
 N2020101814121217
 X0.0980.2190.3000.4240.8111.6380.3860.258
 SD0.0140.0230.0350.0820.1070.6460.0850.025
 Min0.0800.1860.2550.2940.6740.4140.2630.200
 Max0.1250.2810.3750.5731.0522.4720.5350.310
Chasmatopora? angulata
 N3118834373535
 X0.1030.2150.2810.4770.9671.9570.396 
 SD0.0100.0290.0290.0580.1840.6250.151 
 Min0.0840.1760.2340.3730.7030.9390.009 
 Max0.1250.2700.3180.6161.6473.3610.816 

Chasmatopora foerstei sp. nov. Text-figure 1A–F

image

Figure TEXT-FIG. 1.. Chasmatopora foerstei sp. nov. A–D, holotype, USNM 84851, Soldiers’ Home Quarries, Dayton, Ohio, Clinton Group, Silurian. A, obverse surface of entire specimen, locally obscured where light is reflected from cleavage planes on clear calcite where large crystals were removed, ×5. B–D, three of the least weathered regions of the zoarium where the median node-bearing keel is preserved, ×20. E, paratype, USNM 528949, Dayton, Ohio, Clinton Group, Silurian; deep tangential section most of which cuts through the two deeper, lateral rows of zooecia, ×30. F, paratype, USNM 528950, Dayton, Ohio, Clinton Group, Silurian; tangential section that passes through the obverse exozone at left through progressively deeper levels of the endozone to the exozonal laminate skeleton with aligned rows of microstyles comprising the reverse side of branches on the right, × 30.

Download figure to PowerPoint

  • non 1852 Retepora angulata Hall, p. 49, pl. 19, figs 3a–3h.

  • ?1875Retepora angulata? Hall; Hall and Whitfield, p. 111, pl. 5, figs 2–4.

  • 1887 Phylloporina angulata (Hall, 1852); Foerste, p. 151, pl. 15, figs 1, 2.

  • 1893 Phylloporina angulata (Hall); Foerste, p. 600, pl. 28, fig. 1.

  • 1919 Chasmatopora angulata (Hall); Foerste, 1919, p. 369.

Holotype.  USNM 84851 (Foerste 1893, fig. 1), Soldiers’ Home Quarries, Dayton, Ohio, USA, Clinton Group, Silurian.

Paratypes.  USNM 528949, 528950, Dayton, Ohio, USA, Clinton Group, Silurian. (The unit exposed at the Soldiers’ Home Quarries is now assigned to the Brassfield Formation, Llandovery, Silurian, e.g. Ausich 1986).

Description.  Holotype zoarium initially funnel-shaped, degree of flare increasing distally.

Branches unilaminate, sinuous, bifurcating, anastomosed at irregularly spaced intervals. Branch width relatively highly variable for fenestrate bryozoans. Obverse surface of branches with node-bearing median keel; node spacing approximately equal to spacing of zooecial apertures in obverse rows. Four rows of autozooecia, two on either side of branch, with rounded, essentially circular autozooecial apertures more closely spaced along central, more obverse rows than along lateral rows. Fenestrules typically elongate, highly variable in shape and size.

Branches with median planar wall extending from obverse side to reverse side of endozone. Autozooecia budded from median wall, so that branches are bilaterally bilaminate.

In endozone, autozooecia elongate tubular, straight, extending obliquely frontally and distally at approximately 20–30 degrees angle to branch axial plane; length at least six to seven times width; walls approximately 10 μm thick. Pronounced bend but no hemisepta and no change in autozooecial diameter at transition to exozone; in exozone, zooecia separated by extrazooecial laminate wall and zooecial axes curved such that they are progressively at higher angle – eventually perpendicular – to branch surface; peristomes thin, up to about 50 μm high where preserved; exozone relatively thin, up to a little more than 10 per cent total branch width. Diaphragms uncommon but individual diaphragms locally present at transition from endozone to exozone.

Mesozooecia and other heteromorphs apparently absent.

A thin, poorly visible granular wall bounds the reverse surface of the endozone, with several thin, low, longitudinal ridges on the reverse side, covered by exozonal laminate skeleton; crests of the low longitudinal ridges each give rise to a single row of robust microstyles extending through the reverse exozonal laminate skeleton along with abundant, much smaller microstyles.

Scattered megacanthostyles present in extrazooecial skeleton of obverse exozone.

Discussion. C. foerstei differs from C. tenella in having more elongate zooecia, no hemisepta, no increase in zooecial diameter from endozone to exozone, smaller and more closely spaced branches and more elongate fenestrules. It also has more closely spaced keel nodes than reported by Lavrentjeva (1985) for C. tenella.

Measurements. Table 1.

Chasmatopora? angulata (Hall, 1852) Plate 2, figures 1–7

image

Figure EXPLANATION OF PLATE 2.   Figs 1–7. Chasmatopora? angulata (Hall, 1852). Hill’s Mill, Wayne County, New York, USA, Clinton Group, Niagaran, Silurian, 1–3, lectotype, AMNH 30711. 1, 2, obverse surface, ×5. 3, poorly defined zooecial apertures on obverse surface of silicified branch, ×15. 4–7, paralectotype, AMNH 30712. 4, tangential section through obverse exozone (lower left) and endozone (upper region) of branches with possible paired narrow dissepiments linking branches (upper right), ×15. 5, tangential section through endozone and exozone of zooecial chambers (left) in lower, lateral zooecial row bounded by median wall (right), ×65. 6, tangential section through obverse exozone with zooecial cross sections outlined by fine opaque grains, ×65. 7, thick transverse section through two poorly preserved branches, with left branch either broken or a micro-faulted composite of two branches, ×30. Figs 8–10. Esthonioporina quadrata (Bekker, 1921). 8, 10, PIN 3398/82, 8, transverse section across two branches, ×50. 10, tangential section, ×30. Kivioli, Estonia, Kukruse Horizon, Llandeilo, Middle Ordovician. 9, holotype, TU 1110-5, reverse side of specimen, ×5. Kukruse, Estonia, Kukruse Horizon, Llandeilo, Middle Ordovician.

Download figure to PowerPoint

  • 1852 Retepora angulata Hall, p. 49, pl. 19, figs 3a–3h.

  • ?1875Retepora angulata Hall; Hall and Whitfield, p. 111, pl. 5, figs 2–4.

  • ?1883Retepora angulata Hall; Hall, p. 269, pl. 1, figs 1–2.

  • non 1887 Phylloporina angulata (Hall); Foerste, p. 151, pl. 15, figs 1, 2.

  • 1889Subretepora angulata (Hall); Miller, p. 326, fig. 523.

  • non 1893 Phylloporina angulata (Hall); Foerste, p. 600, pl. 28, fig. 1.

  • non 1919 Chasmatopora angulata (Hall); Foerste, 1919, p. 369.

Lectotype.  AMNH 30711 (here designated); from Hill’s Mill, Wayne County, New York, USA, Clinton Group, Niagaran, Silurian.

Paralectotypes.  AMNH 30712 and 30713; from Hill’s Mill, Wayne County, New York, USA, Clinton Group, Niagaran, Silurian.

Description.  Zoarial fragments generally planar, consisting of sinuous, bifurcating unilaminate branches anastomosed at irregularly spaced intervals, with a lagging branch commonly terminated and fused against the side of a leading branch. Zoaria fan-shaped, flat to gently undulose, up to at least 7-cm high and 4-cm wide, with sheets consisting of moderately sinuous, bifurcating unilaminate branches linked at irregularly spaced intervals by anastomosis of a lagging branch terminated and fused against the side of a leading branch and also by narrow dissepiments, at least some of which are doubled. Branch width moderately uniform, relatively high for fenestrate bryozoans. Obverse surface of branches rounded, evenly curved transversely or curved more tightly medially and somewhat less laterally so that a nonkeeled medial ridge is present. Four rows of autozooecia, two on either side of branch, with rounded, essentially circular autozooecial apertures more closely spaced along central, more obverse rows than along lateral rows. Fenestrules typically elongate, highly variable in shape and size.

Branches with median planar wall extending from obverse side to reverse side of endozone. Autozooecia budded at two levels from medial wall, so that branches are bilaterally bilaminate.

In endozone, autozooecia vase-shaped, extending obliquely frontally and distally at about 45 degrees angle to branch axial plane, length three to four times width and walls apparently a little less than 10 μm thick. Pronounced bend and decrease in autozooecial diameter at transition to exozone, where zooecia are separated by extrazooecial laminate wall; axes in exozone relatively straight, essentially perpendicular to branch surface; exozone relatively thin, up to a little more than 10 per cent total branch width. Single endozonal diaphragms present, possibly common.

Mesozooecia and other heteromorphs apparently absent.

Reverse surface of branches thickened by exozonal extrazooecial laminate skeleton; surface with low, closely spaced longitudinal ridges.

Scattered megacanthostyles present in extrazooecial skeleton of obverse exozone.

Discussion.  Only the lectotype and paralectotypes are available for study. All have had the original carbonate skeleton replaced by silica, with substantial degradation in quality of preservation. Skeletal microstructure is not preserved, and boundaries between original skeleton and adjacent matrix of crystalline infilling of chambers have become variably diffuse.

Hall’s Retepora angulata is here questionably assigned to Chasmatopora. Features in common with the type species C. tenella include branch sinuosity, irregularity of fenestrule width and shape, general manner of branch junctions, a median longitudinal wall with two rows of zooecia budded from each side and difference in longitudinal spacing of zooecial apertures in lateral vs. medial rows. Chamber shape, however, is similar to that of Polypora quadrataBekker, 1921, the type species of EsthonioporinaLavrentjeva, 1975, illustrated here in Plate 2, figures 8–10. The shared characters include presence of a median longitudinal wall with two rows of zooecia budded from each side, and intermediate-length zooecia that bud at about 45 degrees to the median wall, reach maximum diameter in the endozone, and are constricted to a smaller diameter at the transition to the exozone, dichotomous branches that seldom are anastomosed but commonly are terminated where a more forwardly extended branch was approached; and branches laterally connected by irregularly spaced, thin dissepiments that commonly appear to be paired. Differences are that E. quadrata has nearly straight branches that are connected by thin dissepiments that vary from widely spaced to pairs or multiples that are very closely spaced, less frequent branch terminations within the meshwork and no apparent difference in longitudinal spacing of apertures between lateral and medial rows.

Measurements. Table 1.

Family PHYLLOPORINIDAE Ulrich, 1890 Genus PHYLLOPORINA Ulrich inFoerste, 1887

Earliest diagnoses.  ‘Zoarium flabellate, perhaps infundibuliform when entire, consisting of anastomosing stems which form elongated, irregular branches. Sections made transversely at some distance from the poriferous side show only one kind of cells. Sections passing just beneath the surface seem to pass through short interstitial cells, which are closed at the surface. Species of this genus have usually been referred to Retepora, Lamarck’. (Foerste 1887, p. 150).

‘Zoaria consisting of somewhat irregularly anastomosing branches, with from two to eight ranges of zooecia on the celluliferous side. Reverse convex, longitudinally striated. Zooecia tubular, with or without diaphragms. Mesopores generally present, sometimes numerous, always closed at the surface; with diaphragms’ (Ulrich 1890, p. 399).

Diagnosis based on current common usage.  Zoaria commonly planar to irregularly undulating or folded sheets. Branches moderately broad but typically <1-mm width; gently to moderately sinuous, bifurcated, anastomosed, anastomosis involving merging of endozones or exozonal fusion and termination of one branch against another; dissepiments not present; fenestrules elongate but highly irregular in outline, from oval to variably polygonal. Three (questionably two) rows of autozooecia distal to branch bifurcations up to at least eight immediately proximal to bifurcations. Obverse surface of branches occupied by typically rounded autozooecial apertures with interspersed apertures of mesozooecia; small acanthostyles present in some. No superstructure present. Autozooecia highly elongate, gently curved with polygonal cross sections, a variable number of diaphragms, with few if any diaphragms other than terminal closures. Mesozooecia originating in exozone or shallow endozone, abundant, filling space between autozooecia on obverse side, polygonal in cross section throughout, wall texture and thickness as for autozooecia, diaphragms lacking to abundant. Heterozooecia similar to autozooecia in endozone but laterally inflated in exozone located in angle of some branch bifurcations may be present. Extrazooecial laminated skeleton apparently restricted to reverse side, typically longitudinally striated although striae may be less conspicuous or absent where reverse wall appreciably thickened.

Phylloporina trentonensis (Nicholson, 1875) Plate 3, figures 1–11

image

Figure EXPLANATION OF PLATE 3.   Figs 1–11. Phylloporina trentonensis (Nicholson, 1875). Trenton Formation, Ordovician, Belleville, Ontario, Canada. 1, 2, neotype, NHM PD 5374. 1, general view of surface with branch obverse surfaces vaguely visible on right and more clearly visible branches on lower left weathered into endozone, ×4. 2, poorly preserved obverse surface of branch but with outlines of autozooecia (larger, circular) and mesozooecia (smaller, polygonal) visible, ×55. 3, NHM PD5375, branches weathered into shallow (left) and deep endozone (centre), ×20. 4, 5, USNM 43440. 4, reverse surface of a well-preserved colony fragment, ×4. 5, detail of reverse surface divided by fine elongate longitudinal and short transverse ridges into cell-like structures, ×15. 6, 9–11, USNM 528948. 6, area illustrated in Ulrich, 1890, pl. 53, fig. 1a, through mesozooecia (e.g. bottom edge, center) and autozooecia in obverse exozone, ×80. 9, longitudinal section with large heterozooecium (gynozooecium?) in fork of a bifurcation (left center), ×40. 10, longitudinal section with large heterozooecium (gynozooecium?) in fork of a bifurcation (top right), ×40. 11, longitudinal section through zone of regeneration within endozone, ×40. 7, 8, USNM 528947. 7, longitudinal section through remnant of thin-walled endozone (left) and thicker-walled exozone (right), illustrated in Ulrich, 1890, pl. 53, fig. 1c, ×20. 8, enlarged view of portion of fig. 7, with few diaphragms in autozooecia and abundant diaphragms in exozonal mesozooecia, ×80.

Download figure to PowerPoint

  • 1875a Retepora Trentonensis Nicholson, p. 37, pl. 2, fig. 4–4b.

  • 1875bRetepora Trentonensis Nicholson; Nicholson, p. 15, pl. 2, fig. 4–4b.

  • 1889Subretepora trentonensis (Nicholson); Miller, p. 326.

  • 1889 Phylloporina trentonensis (Nicholson); Ulrich, p. 47.

  • 1890 Phylloporina trentonensis (Nicholson); Ulrich, pl. 53, fig. 1, 1a–1c.

  • ?1897Phylloporina trentonensis (Nicholson); Whiteaves, p. 162.

Neotype.  Here designated (see discussion) NHM PD5374, Trenton Limestone, Trentonian, Ordovician, Belleville, Ontario, Canada.

Additional material.  NHM PD5375-PD5377, USNM 43440, 528947, 528948, Trenton Limestone, Trentonian, Ordovician, Belleville, Ontario, Canada.

Description.  Overall zoarial shape complexity unknown; fragments up to several cm2 vary from essentially flat to undulose fenestrate sheets consisting of sinuous, bifurcating unilaminate branches anastomosed at irregularly spaced intervals. Branch width variable, relatively broad for fenestrate bryozoans, with commonly four to five rows of autozooecia distal to branch bifurcations and up to at least eight rows proximal to bifurcations. Obverse surface of branches occupied by rounded (circular to elongate oval) autozooecial apertures with interspersed polygonal apertures of mesozooecia. Fenestrules typically elongate, highly variable in shape and size.

Autozooecia highly elongate, gently curved in endozone where length up to at least 16 times width and walls approximately 5 μm thick; a few closely spaced diaphragms present in proximal end of some, and one (or more?) diaphragms present at transition from endozone to exozone. Pronounced bend in autozooecia at transition to exozone; exozonal walls several times thicker than walls in endozone, comprised of poorly defined, highly inclined fine laminae; autozooecial axes in exozone relatively straight at high angle but not perpendicular to branch surface; exozone relatively thin, up to a little more than 10 per cent total branch width.

Mesozooecia restricted to exozone and thin immediately contiguous portion of endozone, abundant, polygonal with slightly concave sides, wall texture and thickness as for autozooecia; those originating in outermost endozone having a few closely spaced diaphragms in proximal end separated by short diaphragm-free distance from abundant and even more closely spaced, locally overlapped diaphragms in exozone; those originating in exozone with closely spaced, locally overlapped diaphragms throughout.

A single heterozooecium with broadly dilated exozonal portion (brood chamber?) commonly present at branch bifurcation, at point on the inner surface of bifurcation fork where branches diverge; outer surface of dilated chamber partially covered by skeletal plate, apparently restricting aperture to approximately the size of autozooecial aperture.

Reverse surface of branches apparently with little or no exozonal laminate skeletal thickening. Longitudinal striae on reverse surface narrow, low and sharp, adjacent striae bridged transversely by similarly narrow, low, sharp structures that are spaced about four times greater than distance between striae so that reverse surface appears organized into longitudinal series of elongate cells.

Discussion.  Original specimens of Retepora trentonensis Nicholson apparently are lost. Benton (1979, p. 58) listed specimens BMNH PD 5374–5377 in a catalogue of H. A. Nicholson’s type and figured specimens, noting that they were collected by (G. J.) Hinde. The catalogue indicated that the specimens matched figures 4–4b of Plate 2 in Nicholson (1875a), with high confidence that the specimens match Nicholson’s illustrations denoted by absence of one or more question marks indicative of varying degrees of uncertainty. However, the original label for NHM PD5374–5377 indicates that the specimens derive from Belleville, not Peterboro’ as indicated in Nicholson (1875a). There is a further problem in that we have been unable to match exactly any portion of the specimens with Nicholson’s drawings. As noted by Benton (1979, p. 17), a Nicholson ‘figure is usually a faithful rendering of the specimen or slide’. The combination of general similarity but lack of exact match with differences in location as given by Nicholson (1875a) and the location as given on the label raises a degree of doubt that the four specimens in the NHM are the original specimens.

We have been unable to locate any specimens of Retepora trentonensis that originate from Peterborough, Ontario, in any of the major collections in Canada, the USNM or the NHM. The NHM specimens are not ideal material from which to designate a neotype because they do not derive from the locality as given by Nicholson (1875a). However, a neotype, ‘as a last resort, and without prejudice to other clarification, [may be chosen from] localities within the known range of the taxon or from which specimens referred to the taxon had been taken’ (ICZN Article 76A.1.4, Ride et al. 2000). We therefore have chosen NHM PD5374 as neotype based on consistency with the characteristics originally described and illustrated by Nicholson (1875a), equivalent geological horizon, relatively close proximity of Peterborough and Belleville (about 70 km distant) and the residual chance that the suite from which it is derived may eventually be determined to be the material on which Nicholson based his illustrations.

The peculiar cellular appearance of the reverse side is because of closely spaced transverse ridges between contiguous longitudinal ridges (striae) bounding vestigial kenozooecia inherited from bifoliate ancestors (Tavener-Smith 1975; Goryunova 1996; McKinney 2000). Other phylloporine genera are more clearly bifoliate, with autozooecia on the obverse side and kenozooecia on the reverse side. Some species of both Pseudohornera (Tavener-Smith 1975; Lavrentjeva 1985) and Thamnocella (unpublished) have larger and more conspicuous kenozooecia in linear rows bounded by striae on the reverse side of the granular wall that comprises the reverse wall of autozooecia. The kenozooecia on reverse sides of these latter genera are elongate tubular. In Pseudohornera, they extend through the moderately thick laminate skeleton on the reverse side and therefore have an endozone and an exozone, whereas in Thamnocella, they are confined to the spaces between the granular-wall longitudinal ridges and are covered over by continuous laminate skeleton.

Measurements. Table 2.

Table 2.   Zoarial and zooecial measurements (in mm) of Retepora trentonensis Nicholson specimens from Belleville, Ontario, Canada in the Natural History Museum, London (NHM PD5374–5376) and the National Museum of Natural History, Washington (USNM 43440, 528947, and 528948).
 AWAL*ASMAWMAL*BWBSFLFWOET
  1. *Measurements of apertural lengths are exaggerated by obliquity of view generated by angle of intersection of zooecia with the obverse surface.

  2. AW, aperture width; AL*, aperture ‘length’; AS, centre to centre spacing of neighbouring apertures; MAW, mesozooecial aperture width; MAL*, mesozooecial aperture ‘length’; BW, branch width; BS, centre to centre branch spacing; FL, fenestrule length; FW, fenestrule width; OET, thickness of exozonal laminate wall on obverse side of branch.

N21312716164937474728
X0.1240.1560.1750.0550.0830.6031.1951.9760.6860.033
SD0.0100.0160.0220.0110.0150.1200.2530.6700.2170.006
Min0.1020.1280.1280.0380.0640.4210.8610.6780.2940.024
Max0.1370.1880.2220.0760.1120.9091.9633.8451.2220.048

Discussion

  1. Top of page
  2. Abstract
  3. The problem
  4. Systematic palaeontology
  5. Discussion
  6. References

Retepora angulata Hall and Phylloporina angulata (Hall) as applied by Foerste (1887) differ in so many character states (Table 3) from R. trentonensis Nicholson that they clearly belong in a different genus. The specimens that Foerste (1887) assigned to Phylloporina angulata (Hall) and are here reassigned to Chasmatopora foerstei sp. nov. comprise the basis for the legal type species of Phylloporina, thereby making Phylloporina a junior subjective synonym of Chasmatopora.

Table 3.   Comparison of basic morphological features of Retepora angulata Hall, Phylloporina angulata (Hall) as used by Foerste (1887), and Retepora trentonensis Nicholson.
SpeciesRetepora angulataHall, 1852Phylloporina angulata (Hall) (Foerste 1887)Retepora trentonensis Nicholson, 1875
Generic assignmentChasmatopora?Chasmatopora‘Phylloporina’
Zoarial meshworkUnilaminate, bifurcated, dissepiment or fusion-linked branchesUnilaminate, bifurcated, anastomosed branchesBilaminate (?), bifurcated, anastomosed branches
Obverse keelPresent?PresentAbsent
Number of rows of zooecia44Variable
Endozonal axial wallPresentPresentAbsent
Autozooecial buddingFrom medial wallFrom medial wallFrom reverse wall
DiaphragmsUncommonUncommonCommon
MegastylesPresentPresentAbsent
Microstyle distribution in lamellar wall of reverse side(not preserved)Longitudinal rowsNot in rows

Many species of Phylloporina have been named since 1890, and the prevailing concept is distinctly different from Chasmatopora. All sufficiently described species or species transferred to Phylloporina since 1890, with one possible exception, have affinities with Ulrich’s intended type species, Retepora trentonensis (Table 4).

Table 4.   Morphological affinity with Retepora angulata Hall vs. R. trentonensis Nicholson of most1 species described as or reassigned to Phylloporina.
SpeciesMorphology related to R. angulataMorphology related to R. trentonensis
  1. Species reassigned to Phylloporina are listed as the original binomen followed by author and date of first consideration as Phylloporina.

  2. e, exterior obverse; e?, obverse keel without nodes, but with contiguous autozooecial apertures; i, interior structures as seen in thin section.

  3. 1Some species are so different from either R. angulata or R. trentonensis that they are omitted from even a general comparison, or they are too poorly characterized to even note similarities to one or the other. These include Retepora tenella Eichwald, 1840 (Männil 1958), Retepora gracilisHall, 1847 (Nickles and Bassler 1900), Retepora inceptaHall, 1847 (Nickles and Bassler 1900), Intricaria clathrataMiller and Dyer, 1878 (Ulrich 1890), Phyllopora variolataUlrich, 1882 (Ulrich 1890), Phyllopora? corticosaUlrich, 1886 (Ulrich 1895), Phylloporina dawsoniUlrich, 1890, Phylloporina orientalisCowper Reed, 1906, Phylloporina megafenestrulaLiu, 1980, Phylloporina obovataLiu, 1980, Phylloporina sinensisLiu, 1980, and Phylloporina robustaZheng, 1990.

Gorgonia? asperaHall, 1847 (as used by Ulrich 1890)i 
Intricaria? reticulataHall, 1847 (as used by Ulrich 1890)e, i 
Retepora hisingeriM’Coy, 1847 (Spjeldnæs 1957) e
Retepora fenestrataHall, 1850 (Nickles & Bassler 1900) e
Retepora asperato-striataHall, 1852 (Ulrich 1890) e, i
Polypora furcataEichwald, 1860 (Toots 1952) e
Phylloporina granistriataUlrich, 1890i 
Phylloporina halliUlrich, 1890 e, i
Phylloporina sublaxaUlrich, 1890 e, i
Phylloporina papillosaBekker, 1921 e
Chasmatopora punctataBekker, 1921 (Toots 1952) e, i
Phylloporina maximaToots, 1952 e
Phylloporina tricellataNekhoroshev, 1955 e, i
Phylloporina aluverensisMännil, 1958 e
Phylloporina carinataMännil, 1958e?e?
Phylloporina nekhorosheviMännil, 1958 e
PhylloporinadevonicaDessilly, 1967 e, i
Phylloporina vagaKopaevich, 1975 i
Phylloporina kinnekullensisBrood, 1980 e, i
Phylloporina longiporaLiu, 1980 e
Phylloporina jaelltjaernensisBrood, 1982 i
Phylloporina certaKopaevich, 1984 i
Phylloporina fragilisLavrentjeva, 1985 i
Phylloporina hillistensisLavrentjeva, 1985 i
Phylloporina indistinctaLavrentjeva, 1985 i
Phylloporina insolitaLavrentjeva, 1985 i
Phylloporina estonicaLavrentjeva, 1988 e, i
Phylloporina sassitoensisErnst and Carrera, 2008 i

Nickles and Bassler (1900) followed Ulrich’s choice of P. trentonensis as type species. Since then, most authors who have given type species of Phylloporina in their articles have incorrectly specified P. trentonensis (Bassler 1935, 1953; Männil 1958; Shulga-Nesterenko et al. 1960; Nekhoroshev 1961; Dessilly 1967; Lavrentjeva 1985; Morozova et al. 2003; Ernst and Carrera 2008). A smaller number have recognized Phylloporina angulata (Hall) as type species (Ross 1963, 1964; Kopaevich 1975; Karklins 1985; Bolton and Cuffey 2005). Bekker (1921) avoided either and instead without comment gave Phylloporina granistriataUlrich, 1890 as the type species.

The characteristics of Retepora angulata have previously been so poorly known that even those who have given Phylloporina angulata as the type species have named new species or discussed established species that have affinities with P. trentonensis rather than with P. angulata. With only a couple of ill-defined 19th century exceptions, the only species that has been either reassigned to Phylloporina or was newly described as Phylloporina and that has generic characteristics broadly related to Retepora angulata is R. angulata itself (Table 4).

We therefore intend to petition the International Commission on Zoological Nomenclature that Reteporina angulata be set aside and replaced by R. trentonensis as type species of Phylloporina, as is possible under Article 81.1 of the International Code of Zoological Nomenclature. Until that time, according to Article 82.1 of the Code, ‘When a case is under consideration by the Commission, prevailing usage ... of names is to be maintained until the ruling of the Commission is published’. Prevailing usage in this case means – for now – the retention in Phylloporina of species allied with Retepora trentonensis rather than with R. angulata.

Acknowledgements.  We thank Neil Landman and Bushra Hussaini (AMNH) for access to specimens; Jo Ann Sanner (USNM), Paul Taylor (NHM), Ursula Toom (Tallin), Olga Weiss and Dmitry Lisitsyn (PIN) for both access to and photography of specimens; Anthony Love and Hou Guichuan of Appalachian State University for photographic assistance; and Paul D Taylor and Joe Pachut who provided critical reviews of the manuscript.

Editor. Lyall I. Anderson

References

  1. Top of page
  2. Abstract
  3. The problem
  4. Systematic palaeontology
  5. Discussion
  6. References
  • AUSICH, W. I. 1986. Early Silurian inadunate crinoids (Brassfield Formation, Ohio). Journal of Paleontology, 60, 719735.
  • BASSLER, R. S. 1911. The Early Paleozoic Bryozoa of the Baltic Provinces. United States National Museum, Bulletin, 77, 382 pp.
  • BASSLER, R. S. 1935. Bryozoa (Generum et Genotyporum Index et Bibliographia). In QUENSTEDT, W. (ed.). Fossilium Catalogus 1: Animalia, Pars 67. W. Junk N. V., Den Haag, 229 pp.
  • BASSLER, R. S. 1953. Bryozoa. In MOORE, R. C. (ed.). Treatise on invertebrate paleontology, Part G, Bryozoa. The Geological Society of America, New York and The University of Kansas Press, Lawrence, 253 pp.
  • BEKKER, H. 1921. The Kuckers Stage of the Ordovician rocks of NE Estonia. Acta et Commentationes Universitatis Dorpatensis, A2, 92 pp.
  • BENTON, M. J. 1979. H A Nicholson (1844–1899), invertebrate palaeontologist: bibliography and catalogue of his type and figured material. Royal Scottish Museum Information Series, Geology, 7, 94 pp.
  • BOLTON, T. F. and CUFFEY, R. J. 2005. Bryozoa of the Romaine and Mingan Formations (Lower and Middle Ordovician) of the Mingan Islands, Quebec, Canada. 2541. In MOYANO, H. I., CANCINO, J. M. and WYSE JACKSON, P. N. (eds). Bryozoan studies 2004. A. A. Balkema Publishers, Leiden, 411 pp.
  • BROOD, K. 1980. Bryozoa from the Upper Ordovician Dalminitina Beds of Kinnekulle, Sweden. Geologiska Föreningens i Stockholm Förhandlingar, 102, 2735.
  • BROOD, K. 1982. Bryozoa from the Klingkalk at Jälltjärn in Dalarna, Sweden. Acta Universitatis Stockholmiensis Stockholm Contributions in Geology, 37, 4348.
  • COWPER REED, F. R. 1906. The lower Palaeozoic fossils of the northern Shan States, Burma. Geological Survey of India, Memoirs, Palaeontologia Indica, 3, 154 pp.
  • DESSILLY, E. 1967. Les bryozoaires devoniens de la Belgique. La presence du genre “Phylloporina” dans le Couvinien de la Belgique. Institut royal des Sciences naturelles de Belgique, Bulletin, 43, 16.
  • EICHWALD, E. 1840a. Über das silurische Schichtensystem in Esthland. Medizinischen Adakemie zu St. Petersburg, St. Petersburg, 210 pp.
  • EICHWALD, E. 1840b. Sur le Systéme Silurien de l’Esthonie. l’Académie de Médecine de St.-Petersbourg, St. Petersburg, 222 pp.
  • EICHWALD, E. 1842. Die urwelt Russlands, durch abbildungen Erlaeutert. Zweites Heft. Kaiserlichen Akademie der Wissenschaften, St. Petersburg, 184 pp.
  • EICHWALD, E. 1855. Beitrag zur geographischen Verbreitung der fossilen Thiere Russlands. Alte Periode. Société Impériale des Naturalistes de Moscou, Bulletin, 28, 433466.
  • EICHWALD, E. 1860. Lethaea Rossica ou Paléontologie de la Russie. Premier Volume, Ancienne Période. E. Schweizerart, Stuttgart, 359 pp.
  • ERNST, A. and CARRERA, N. 2008. Cryptostomid bryozoans from the Sassito Formation, Upper Ordovician cool-water carbonates of the Argentinian Precordillera. Palaeontology, 51, 11171127.
  • FOERSTE, A. F. 1887. The Clinton Group of Ohio – Part III. Bulletin of the Scientific Laboratories of Denison University, 2, 149176.
  • FOERSTE, A. F. 1893. Fossils of the Clinton Group in Ohio and Indiana. Ohio Geological Survey, Report, 7, 516601.
  • FOERSTE, A. F. 1919. Silurian fossils from Ohio, with notes on related species from other horizons. The Ohio Journal of Science, 19, 367404.
  • GORYUNOVA, R. V. 1996. Morphology, systematics, and phylogeny of Bryozoa. Paleontologicheskogo Instituta Akademiya Nauk SSSR, Trudy, 208, 152 pp.
  • HALL, J. 1847. Palaeontology of New York. Volume 1. Containing descriptions of the organic remains of the lower division of the New-York system. D. Appleton & Co., Albany, 337 pp.
  • HALL, J. 1850. Description of new species of fossils, and observations upon some other species not previously well known, from the Trenton Limestone. 173183. Third Annual Report of the Regents of the University, on the condition of the State Cabinet of Natural History, and the historical and antiquarian collection annexed thereto. Webb, Parsons & Co., Albany, 183 pp.
  • HALL, J. 1852. Palaeontology of New York. Volume 2. Containing descriptions of the organic remains of the lower middle divisions of the New York System. D. Appleton & Co., Albany, 362 pp.
  • HALL, J. 1883. Van Cleve’s fossil corals. Indiana Department of Geology and Natural History, Twelfth Annual Report, 239270.
  • HALL, J. and WHITFIELD, R. P. 1875. Descriptions of Silurian fossils. Geological Survey of Ohio, Report, 2, 65161.
  • HARMER, S. F. 1933. The genera of Reteporidae. Zoological Society of London, Proceedings, 1933, 615627.
  • KARKLINS, O. L. 1985. Bryozoans from the Murfreesboro and Pierce Limestones (Early Black Riveran, Middle Ordovician), Stones River Group, of central Tennessee. Paleontological Society Memoir, 15, 42 pp.
  • KENT, L. S. 1982. Type and figured fossils in the Worthen Collection at the Illinois State Geological Survey. Illinois Department of Energy and Natural Resources State Geological Survey Division, Circular, 524, 65 pp.
  • KOPAEVICH, G. V. 1975. Silurian Bryozoa of Estonia and Podolia. Akademiya Nauk SSSR Paleontologicheskogo Instituta, Trudy, 151, 155 pp.
  • KOPAEVICH, G. V. 1984. Atlas of Ordovician, Silurian, and Devonian Bryozoa of Mongolia. Sovmestnaya Sovetsko-Mongolskaya Paleontologicheskaya Ekspeditsiya, Trudy, 22, 164 pp.
  • LAMARCK, J. B. 1801. Systême des animaux sans vertebres ou tableaux général des classes, des orders et des genres de ces animaux. Deterville, Paris, 432 pp.
  • LAVRENTJEVA, V. D. 1975. On a new bryozoan genus in the Family Phylloporinidae. Paleontologicheskiy Zhurnal, 1975, 138140.
  • LAVRENTJEVA, V. D. 1979. Phylloporinina, a new suborder of Palaeozoic Bryozoa. Paleontologicheskiy Zhurnal, 1979, 5968.
  • LAVRENTJEVA, V. D. 1985. Bryozoa of the suborder Phylloporinina. Akademiya Nauk SSSR Paleontologicheskogo Instituta, Trudy, 214, 101 pp.
  • LAVRENTJEVA, V. D. 1988. New Upper Ordovician Phylloporinina (Bryozoa) from Estonia. Paleontologicheskiy Zhurnal, 1988, 100103.
  • LINDAHL, J. 1890. Letter of transmittal. Illinois Geological Survey, 8, vxi.
  • LIU XIAOLIANG 1980. Bryozoa. 189254. Paleontological atlas of northeast China. Volume 1. Paleozoic volume. Geological Publishing House, Beijing, 686 pp.
  • MÄNNIL, R. M. 1958. New Bryozoa of the order Cryptostomata from the Ordovician of Estonia. Akademii Nauk Ėstonskoï SSR 7 Seriya Tekhnicheskikh i Fiziko-Matematicjeskikh Nauk, Izvestiya, 4, 330347.
  • M’COY, F. 1847. On the fossil botany and zoology of the rocks associated with the coal of Australia. Annals and Magazine of Natural History, Series 1, 20, 226236.
  • McKINNEY, F. K. 2000. Phylloporinids and the phylogeny of Fenestrida. 5465. In HERRERA CUBILLA, A. and JACKSON, J. B. C. (eds). Proceedings of the 11th International Bryozoology Association Conference. Smithsonian Tropical Research Institute, Balboa, 448 pp.
  • MILLER, S. A. 1889. North American geology and palaeontology for the use of amateurs, students, and scientists. Privately Published, Cincinnati, 718 pp.
  • MILLER, S. A. and DYER, C. B. 1878. Contributions to palaeontology. No. 2. Privately Published, Cincinnati, 11 pp.
  • MOROZOVA, I. P., GORYUNOVA, R. V. and ARIUNCHIMEG, Ya 2003. Bryozoa. In ROZANOV, A. Yu (ed.), Paleontologiya Mongolii. Moskva Nauka, Moscow, 169 pp.
  • NEKHOROSHEV, V. P. 1936. Some Lower Silurian Bryozoa from the Carnic Alps. Tsentralnogo Nauchno-Issledovatelskogo Geologo-Razvedochnogo Instituta, Trudy, 61, 522.
  • NEKHOROSHEV, V. P. 1955. Order Cryptostomata. 5560. In NIKIFOROVA, O. I. (ed.). Polevoy atlas ordovikskoy i siluriyskoy fauny Sibirskoy platformy. Gosgeoltekhizdat, Moscow, 140 pp.
  • NEKHOROSHEV, V. P. 1961. Ordovician and Silurian Bryozoa from the Siberian Platform. Vsesoyuznogo Nauchno-Issledovatelskogo Geologicheskogo Instituta, Trudy, 41, 246 pp.
  • NICHOLSON, H. A. 1875a. Descriptions of new species and of a new genus of Polyzoa from the Palaeozoic rocks of North America. Geological Magazine, New Series, Decade 2, 2, 3338.
  • NICHOLSON, H. A. 1875b. Report upon the palaeontology of the Province of Ontario. Hunter, Rose and Company, Toronto, 96 pp.
  • NICKLES, J. M. and BASSLER, R. S. 1900. A synopsis of American fossil Bryozoa, including bibliography and synonymy. United States Geological Survey, Bulletin, 173, 663 pp.
  • RIDE, W. D. L., COGGER, H. G., DUPUIS, C., KRAUS, O., MINELLI, A., THOMPSON, F. C. and TUBBS, P. K. 2000. International Code of Zoological Nomenclature, Fourth Edition. The International Trust for Zoological Nomenclature, London, 306 pp.
  • ROSS, J. P. 1963. Ordovician cryptostome Bryozoa, standard Chazyan Series, New York and Vermont. Geological Society of America, Bulletin, 74, 577608.
  • ROSS, J. P. 1964. Champlainian cryptostome Bryozoa from New York State. Journal of Paleontology, 38, 132.
  • SHULGA-NESTERENKO, M. I. 1952. New Lower Permian Bryozoa from the Pre-Urals. Akademiya Nauk SSSR Paleontologicheskogo Instituta, Trudy, 37, 84 pp.
  • SHULGA-NESTERENKO, M. I. 1955. Carboniferous Bryozoa of the Russian Platform. Akademiya Nauk SSSR Paleontologicheskogo Instituta, Trudy, 57, 207 pp.
  • SHULGA-NESTERENKO, M. I., NEKHOROSHEV, V. P., MOROZOVA, I. P., ASTROVA, G. G. and SHISHOVA, N. A. 1960. Order Cryptostomata. 7293. In SARYCHEVA, T. G. (ed.). Osnovy paleontologii, spravochnik dlya paleontologov I geologov SSSR; v. 7, Mshanki, brakhiopody; prilozhenie; Foronidy. Izdatelstvo Akademii Nauk, SSSR, Moscow, 343 pp.
  • SPJELDNÆS, N. 1957. A redescription of some type specimens of British Ordovician Bryozoa. Geological Magazine, 94, 364376.
  • TAVENER-SMITH, R. 1975. The phylogenetic affinities of fenestellid bryozoans. Palaeontology, 18, 117.
  • TOOTS, H. 1952. Bryozoen des estnischen Kukersits. Geologischen Staatsinstitut in Hamburg, Mitteilungen, 24, 113137.
  • ULRICH, E. O. 1882. American Paleozoic Bryozoa. Cincinnati Society of Natural History, Journal, 1882, 121175.
  • ULRICH, E. O. 1886. Report on the Lower Silurian Bryozoa with preliminary descriptions of the new species. Minnesota Geological and Natural History Survey, Annual Report, 14 (for 1885), 57103.
  • ULRICH, E. O. 1889. Contributions to the micro-palaeontology of the Cambro-Silurian rocks of Canada. Part 2. Geological and Natural History Survey of Canada, Montreal, 57 pp.
  • ULRICH, E. O. 1890. Palaeozoic Bryozoa. Illinois Geological Survey, 8, 283688.
  • ULRICH, E. O. 1895. On lower Silurian Bryozoa of Minnesota. Minnesota Geological and Natural History Survey, Final Report, 3, 96332.
  • WHITEAVES, J. F. 1897. The fossils of the Galena-Trenton and Black River formations of Lake Winnipeg and vicinity. Geological Survey of Canada Palaeozoic Fossils, 3, 129242.
  • ZHENG YUEJUAN 1990. Ordovician bryozoans from Nei Mongol – Hinggan Ling Range. Shenyang Institute of Geology and Mineral Resources, Bulletin, 19, 6169.