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Show 290 MR. G. S. BRADY ON EUROPEAN CYPRIDINID/E. [Apr. 4, cornis is at some seasons abundant on certain parts of the British coast, B. brenda has never been met with, except very sparingly, and in only two localities. The following is a brief abstract of Sars's remarks on this subject : - " I had long remarked that all the individuals of Philomedes longicornis appeared to be males ; there were no egg-bearing females ; but it did not occur to m e to look for the female in so different a form as C. globosa (brenda), especially as I had already found what appeared to be the male of that species. But we find in other Crustacea (Apseudes anomalies and certain Cumacea) two forms of males,-one and much the commoner form being very similar to the female, the other and scarcer differing in many important details, especially in the great development of the eyes and antennae. The parts of the Cypridinidae which appear to be least liable to alteration are the mandible-palp, the last pair of jaws, the ringed appendage (" oviferous foot"), and the postabdominal lamina; and these parts are all alike in Cypridina globosa and Philomedes longicornis. A further confirmation of the truth of m y view is, that I have found a similarly formed male of a closely allied species, P. lilljeborgii. This differs from P. longicornis in having the postero-inferior spine of the shell more strongly developed, the ringed appendage showing also the same distinctive marks as does that of the female, in having only about nine spines instead of thirty as in C. globosa." Among a number of Ostracoda dredged at various depths in the Fosse de Cap Breton (Bay of Biscay) by M . le Marquis de Folin, and sent to me for identification, were several specimens of a very remarkable undescribed species, one of which was so far different in size and form from the rest, though retaining the same characters as to shell-sculpture, that I immediately took it to be the male of the more abundant female form. And on further examination the smaller example proved to have all the anatomical characters of Lill-jeborg's genus Philomedes, while the larger ones belonged to Bradycinetus, Sars. The shell-structure is here of so novel a type (no similar deep excavation and ribbing having heretofore been noticed among the Cypridinidae) that I could no longer doubt as to the sexual relations of Philomedes and Bradycinetus in this instance ; and I was therefore disposed to regard Sars's case as proved with respect also to P. longicornis and B. brenda. This conclusion, however, I had adopted too hastily, as will presently appear; for in the same gathering (Cap Breton) were found several examples of a Philomedes (Pl. X X V I . fig. 1) agreeing in general aspect with "P. longicornis," but rounder in lateral outline and more tumid, having also a reticulated shell-structure exactly the same as that of the common form, but differing constantly in the presence of two well-marked sharp spines on the postero-superior and postero-inferior angles of the shell. Anatomical investigation showed that this was in fact the true female of P. longicornis, the only appreciable differences consisting in the shortened filaments of the upper antennae, and the smaller development of the eyes, mandibular feet, and secondary branch of lower antenna, the vermiform appendage and abdominal |