XXX.—On the Feeding Mechanism of Certain Marine Ostracods

Extract

Systematists agree that the Asteropid Ostracods are closely related to the other subfamilies of the Cypridinidæ. Asterope agrees with Cypridina in the form of its antennules and antennæ, in the peculiar bottle-brush second trunk limb so characteristic of the Cypridinidæ, and, to a lesser extent, in the gnathobasic armature of its mandibles, and yet, in its mouth parts, especially the maxillules and maxillæ, Asterope differs totally from Cypridina, and, in fact, from any other Crustacean. Attempts to homologize these limbs with those of other Ostracoda have been made by many systematists, but without much success. Thus recently Skogsberg (1920, p. 39), referring to the maxillule of Asterope, states: “This far-reaching modification and the total lack of known transitional forms makes any attempt at homologization merely a caprice, at worst obviously incorrect, at best unverifiable”; and Hansen (1925, p. 69), discussing the maxillule, states that “the chitinization is weak and lobes rudimentary that it may be impossible to interpret all points with real certainty before forms intermediate between Cypridina and Asterope have been discovered—if they exist.” Despite this impasse along purely morphological lines, I think it is possible, by studying the feeding mechanisms, to establish the relationship between the Asteropid and Cypridinid constitution.