XV.—The Structure and Relationships of Lamellibranchs possessing a Cruciform Muscle

Abstract

In the first decade of the present century Bloomer reported in a series of concise papers (for which see the list of references) the results of his investigations into the structure of the majority of the lamellibranchs which were then classified in the family Solenidæ. In addition to a general description of the external anatomy of these bivalves he paid especial attention to the details of the musculature, to the course of the alimentary canal and the structure of the stomach, while he gave rather generalised accounts of the nervous system and of the arrangement of the circulation, in which he almost entirely followed the previous work of Ménégaux (1890). Bloomer made little attempt to view as a whole the information which had been gathered together as a result of these years of work; the only papers which he published that can be regarded as dealing with his results from a general standpoint being a short one (1903b) on the classification of the British species of the genus Solen, and a second (1903c), equally brief, on the origin and function of the small fourth pallial aperture which is a marked feature of the anatomy of certain members of the family. This he proved to be a separated portion of the pedal gape, not homologous with the similar structure lying in a more posterior position in some of the Anatinacea and in Lutraria.