OSTRACODA. 5 



of the adult. But one or two small specimens which occurred along with P. 

 orbicularis, and which I at first took to be the young of that species, were very 

 distinctly angulated posteriorly, and I now think that they belong probably to the 

 following species P. assimilis, especially as they have not the villous covering of 

 P. orbicularis. 



Philomedes assimilis. 

 (Plate I., figs. 16-21. Plate II., figs. 1-6.) 



Shell of the female seen from the side (Plate II., fig. 1) oblong, subcireular, height 

 equal to two-thirds of the length, anterior extremity sharply angulated below at its 

 junction with the wide truncated rostrum, posterior sloping steeply and forming a some- 

 what rounded, prominent angle at its ventral end ; dorsal margin strongly arched, 

 highest in the middle, ventral evenly but less strongly convex, terminating in front in 

 a deep subrostral sinus and behind in an obtusely angular process. Seen from above 

 (fig. 2) the outline is oblong, ovate, twice as long as broad, greatest width situated 

 in the middle, anterior extremity obtusely pointed, posterior produced and mucronate, 

 lateral margins evenly arcuate. The shell of the male (fig. 3) much longer in 

 proportion to the height, rostrum and subrostral sinus much less pronounced, 

 posterior extremity more narrowed and having a larger and more rounded ventral 

 prominence ; the squamous, marginal laminae of the rostrum are marked with numerous 

 hair-like striae and are closely punctated (fig. 4). The limbs and appendages do 

 not present any special specific characters, but the hairs at the base of the claws 

 of the post-abdomen of the male are more than usually conspicuous (fig. 5). 

 Length of the female, 1 • 8mm. 



The stations at which P. assimilis was taken were all in Winter Quarters : — 



September 30, 1903.— No. 12 hole, D. net 246. 



Hut Point.— September 13, 1902, D. net. 



Hut Point.— February 13, 1904, D. net 264. 



10 Fathoms, March 19, 1902. 



November 28, 1902, D. net. 



May 23, 1902, and February 13, 1904. 



]2 Hole, D. net, September 8, 1903. 



Philomedes Antarctica. 



(Plate III., figs. 1-10.) 



Shell of the female seen from the side, broadly subovate (fig. 2), with a prominent 

 beak, a deep subrostral sinus, and an obtusely prominent postero-ventral angle, greatest 

 height situated in the middle, and equal to about two-thirds of the length ; anterior 

 extremity rather narrower than the posterior, sloping steeply from the dorsum to form 

 the angularly prominent beak ; posterior subtruncate, slightly sinuated, rounded off" 

 dorsally, but terminated ventrally by a rounded, backwardly produced prominence ; 



VOL. III. L 



