CONCHIFERA. 463 
Batissa, Gray. Anterior lateral teeth short ; under ones long. 
Velorita, Gray. Anterior laterals thick and triangular. 
Distribution, 180 species. Tropical America (eastern), Egypt, 
India, China, Australia, Pacific Islands. In the mud of rivers, 
and in mangrove swamps, usually near the coast. C. consobrina 
ranges from Heypt to Cashmere and China, and is found fossil 
in the Pliocene formations of England,* Belgium, and Sicily. 
Fossil, 105 species. Wealden—. LHurove, United States. 
? CYRENOIDES, Joannis. 
Synonym, Cyrenella, Desh, 
Type, C. Dupontiu, Pl. XIX., Fig. 19. 
Shell orbicular, ventricose, thin, eroded at the beaks; epi- 
dermis dark olive; ligament external, prominent, elongated ; 
cardinal teeth 3.2, the central tooth of the right valve bifid; 
muscular impressions long, narrow; pallial line simple. 
Animal with the mantle open in front and below, margin 
simple, siphons short, united; palpi moderate, narrow; gills 
yery unequal, narrow, united behind ; foot cylindrical elongated. 
Distribution, 4 species. River Senegal. The marine species 
are Diplodonte. 
Fossil, 1 species. Europe. 
Famity XII*.—CyYPprRiInipz. 
Shell regular, equivalve, oval or elongated; valves close, 
solid; epidermis thick and dark; ligament external, conspicu- 
ous ; cardinal teeth 1—3 in each valve, and usually a posterior 
lateral tooth ; pedal scars close to, or confluent with, the 
adductors; pallial line simple. 
Animal with the mantle-lobes united posteriorly by a curtain, 
pierced with two siphonal orifices; foot thick, tongue-shaped ; 
gills 2 on each side, large, unequal, united behind, forming a 
complete partition; palpi moderate, lanceolate. 
One half the genera of this family are extinct, and the rest 
(excepting Circe) were more abundant in former periods than at 
the present time. Cyprina and Astarte are boreal forms; Circe 
and Cardita abound in the Southern seas. 
Cyprina, Lamarck. 
Etymology, Kuprinos (from Kupris), related to Venus. 
Type, ©. Islandica, Pl. XTX., Fig. 22. 
* Associated with the bones of Elephas meridionaiss, Rhinoceros leptorhinus, 
Niastodon Arvernensis, Hippopotamus major, §c. 
