REPORT ON THE OSTRACODA. 159 



secondary braueli, 6 maudibular foot, 7 maxilla of first pair, 8 maxilla of second parr, 

 9 maxilla of third pair, 10 male copulative organ, 11 portion of postabdominal lamina 

 showing six claws in sita, with scars of attachment of the remainder.] 



Phllomedes, Lilljeborg (1853). 



Shell of moderate strength and density, notch broad, anterior extremity obtuse, 

 posterior extremity mostly produced or angulated ; anterior antennse six-jointed, in the 

 female short and stout, and bearing several subequal terminal setae of moderate length ; 

 in the male more elongated, two of the terminal setse of excessive length, the antepen- 

 ultimate joint bearing a stout and densely setose auditory filament. Natatory branch of 

 posterior antenna nine-jointed, in the female having the first joint very long, the rest 

 short and subec[ual ; in the male the first and third joints long, second much shorter, the 

 ■ rest short and subequal ; secondary branch in the female, indistinctly jointed, setose ; in 

 the male, long, three-jointed, the last joint forming an opposable curved claw. Mandibular 

 feet nearly alike in both sexes, in the female armed with mandibuliform processes and 

 spines ; in the male, bearing on the basal joint a small tubercle with two short hairs 

 representing the incisive portion of the mandible proper ; penultimate joint shorter than 

 in Cypridina, the anterior marginal setse fewer and fasciculate ; first pair of jaws slender, 

 palp bearing only a small trisetose lobe ; second pair in the female only, armed with 

 mandibuliform processes and spines. Third pair as in Cypridina. Eyes large, distant, 

 placed at the sides of the animal near the centre of each valve. " Animal swimming 

 with long jerks" (Sars). 



This genus was established by Professor Lilljeborg for the reception of a species called 

 by that author Fhilomedes longicornis, but which is identical with the previously-described 

 Cypridina inter p)uncta, Baird. 



The females of this genus differ, to a certain extent, both in form of shell and internal 

 structure, from the males, and are seldom or never met with except on the bottom ; the 

 males, on the contrary, being active swimmers, are often taken abundantly in the surface- 

 net. Professor G. 0. Sars, noticing that he never obtained any egg-bearing females of 

 Fhilomedes longicornis, has expressed an opinion that Cypridina glohosa (brenda) is the 

 true female of that animal. I have abeady, in the Proceedings of the Zoological Society, 

 April 4, 1871, stated my reasons for dissenting from that view, and have traced, as I 

 think, with sufiicient clearness, the true sexual relations of several reputed distinct species. " 

 Into this question I need not, therefore, here enter at greater length. 



Cypridina olivacea, Dana, Professor Sars thinks fairly referable to the genus Pliilo- 

 medes. I am disposed, however, to think that this species may more properly be assigned 

 to the genus Asterope. One very fine new species, Pkilomedes ivyville-thomsoni (mihi), 

 doubtless belonging to the genus Phllomedes, is described below, and I have ventured to 



