KNOWN SPECIES OF MARINE OSTRACODA. 387 



aspect oval, fully twice as long as broad, pointed in front, mucronate behind. Surface 

 smooth, white. 



Length xj in- (2 mm.). 



Hab. Pescadore, China. Taken in the towing-net {Mr. A. Adams). 



3. Cypridina bairdii, n. sp. (PI. LXII. fig. 7, a-m.) 



Carapace horny, suborbicular, convex, about one-third longer than broad, obtusely 

 mucronate posteriorly, flattened in front, Dorsal and ventral margins convex, uniting 

 behind to form a rather broad, obtuse, terminal spine. The anterior margin is sulcate 

 in the middle. Beak short and broad ; notch rather small. Seen from the ventral 

 surface, the outline of the carapace is oval, oblong ; its anterior extremity truncate, 

 posterior subacute. End view oval, with broad, truncate extremities. The right valve 

 bears on its ventral margin, a little in front of the beak, a rounded prominence, which 

 is absent from the left valve. The left valve is, however, larger and more rounded in 

 outline, so that it overlaps the projections of the opposite valve much in the same way 

 as the large and rounded valve of Bairdia overlaps the smaller and angular one. Surface 

 ornamented with large and thickly set circular pits, which, on the ventral and dorsal 

 aspects, coalesce so as to form jagged furrows. 



Length xg- in. (2*54 mm.). 



Hab. Pescadore, China. Many specimens taken in the towing-net (Mr. A. Adams). 



Genus Heterodesmus, nov. gen. 



Carapace subglobose. Dorsal margin slightly arched, forming at its extremities two 

 largely developed hinge-processes ; the anterior process somewhat waved and scroll- 

 like ; the posterior a truncate cone, projecting directly upwards. Ventral margin 

 strongly arched. Animal unknown. 



Heterodesmus adamsii, n. sp. (PI. LXII. fig. 6, a-h.) 



Carapace subquadrilateral, convex; length about one-fourth greater than the breadth. 

 Ventral margin prominently arched. Dorsal margin slightly arched, terminating pos- 

 teriorly in a strong, truncated, conical process, which projects upwards beyond the plane 

 of the dorsum. The anterior hinge-process forms a swollen, scroll-like protuberance 

 situated at the upper angle of the anterior margin, and hollowed out beneath so as to 

 form a somewhat flattened beak with a subjacent shallow notch. Posterior margin 

 straight, formed chiefly by the posterior hinge-process. Dorsal aspect broadly ovate, 

 once and a half as long as broad, somewhat narrowed in front. Surface smooth. 

 Colour light buff, mottled with patches of a rather deeper tint. Animal unknown. 



Length ^s" in. (1'9 mm.). 



Hah. Japan. Taken in the towing-net {Mr. A. Adams). 



This curious species is nearly allied to Entomoconchus scouleri, M'Coy, but, so far as 



3e2 



