The development of Clonograptus tenellus and Adelograptus hunnebergensis



The development of Clonograptus tenellus Linnarsson and Adelograptus humnebergensis (Moberg) is described for the first time. The material comprises well-preserved isolated specimens from the Shineton (Tremadoc) Shales of Cherme's Dingle and Lady Covert, near- Leighton, Shropshire. Two new morphological terms, the cauda and the conus, have been introduced for the adequate description of the prosicula. This material demonstrates that the nema is a hollow tube with a passage into the apex of the prosicula, and an open growing end. The term nematocaulus has been applied to the soft tissue which secreted the nema. The mode of development and the internal stolon system suggested by Bulman (1949) have been confirmed. Early growth stages of this material are compared with those of Rhabdopleura compacta Hincks.