58 Zoological Society. 



3. Cythereis fistulosa, Baird. 



Carapace valves nearly quadrilateral, elongate. Anterior extremity 

 a little more rounded than posterior, and armed with seven or eight 

 small teeth ; posterior extremity armed with five or six larger teeth. 

 Dorsal and ventral margins nearly straight. Surface of valves gra- 

 nular and ornamented by four elevated straight ridges, which are per- 

 forated near their margins with small round holes. 



Hub. Manilla. Mr. Williamson's collection. 



4. Cythereis prava, Baird. 



Carapace valves suhquadrangular. Anterior extremity considerably 

 broader than posterior, rounded, smooth round the edge, and having 

 a broad flat margin beset on inner edge with small round tubercles ; 

 posterior extremity emarginate, and furnished on inferior half with 

 several short teeth. Valves extremely gibbous in centre, and the 

 surface very rough, wrinkled, and tubercled. 



Hab. Tenedos. Mr. "Williamson's collection. 



5. Cythereis deformis, Baird. 



Carapace valves ovate, short and gibbous ; the two extremities of 

 nearly the same size. Dorsal and ventral margins nearly straight. 

 Surface of valves very coarsely granulated and tubercled ; roughly 

 ridged, but the ridges not perforated as in the preceding species. 



Hab. Manilla. Mr. "Williamson's collection. 



6. Cythereis senticosa, Baird. 



Carapace valves flat, ovate. Anterior extremity broader than poste- 

 rior, and rounded. Dorsal margin sloping towards posterior extre- 

 mity; ventral nearly straight. The surface of the valves is very rough, 

 wrinkled, and beset all over, but especially near the margins, with 

 strong spinous lacinise. 



Hab. Tenedos. Mr. "Williamson's collection. 



Genus Cypridina, M. -Edwards. 



1. Cypridina Zealanica, Baird. 



Carapace valves of an oval form, somewhat flattened, but convex 

 in the centre and striated ; the striae are numerous, close-set, and 

 of a waved appearance. Surface of valves covered with minute punc- 

 tations, which probably give origin in the fresh state to short hairs, 

 though they are not visible in the dried specimens. The anterior ex- 

 tremity is slightly narrower than posterior. The whole carapace is of 

 a uniform white colour. Natural size one-fourth of an inch long and 

 one-fifth of an inch broad. 



Hab. New Zealand. Two specimens were sent to the British Mu- 

 seum by the Rev. R. Taylor, of Waimati in New Zealand, along with 

 a collection of marine and freshwater shells, but without any history 

 attached to them. 



2. Cypridina interpuncta, Baird. 



Carapace valves oval. Anterior extremity narrower than posterior ; 



