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THE STOMACH IN THE PROTOBRANCHIA AND SEPTIBRANCHIA (LAMELLIBRANCHIA)

Authors


SUMMARY

  • 1Detailed studies have been made of the structure and function of the stomach in the two protobranchs, Nucula nucleus L. and Nuculana minuta (Müller).
  • 2The structure of the stomach in the Protobranchia was described and figured, and defined as Stomach Type I.
  • 3The stomach of the septibranch Cuspidaria cuspidaia (Olivi) was similarly examined, described and figured, and was defined as Stomach Type II.
  • 4The stomachs of the Protobranchia and Septibranchia were compared and it was noted that there were several common features. Further resemblances were found in the structure of the digestive diverticula, and in the muscular pumping of water by the ctenidium (Nuculana) or by the septum (Cuspidaria).
  • 5It was concluded that there is a strong suggestion of phylogenetic relationship between the Protobranchia and the Septibranchia.
  • 6The view, previously stated by Yonge, that there was no justification for linking the Protobranchia and the Arcacea in an order Taxodonta was upheld.

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