CONCHIFERA OE BIYALYES. 87 



bosses eroded; an epidermis. Animal similar 

 to the Cyclas. — 16 species recent, and 11 

 fossil. 



Natives of warm climates, particularly of 

 Asia : they attain a much greater size than the 

 last genus, and have the interior of a beautiful 

 violet colour, the outside being occasionally 

 tinged with the same. They are fluviatile. 



45. Galathea. — Shell equivalve, thick, 

 and solid, somewhat trian- 

 gular, nearly equilateral, and 

 covered by a greenish horny 

 epidermis, cardinal teeth two 

 in one valve, and three in the 

 other, lateral teeth at some distance, ligament 

 exterior, projecting, and swollen. Animal, foot 

 large and oblong. — 1 species recent. 



Only one species is known of the Galathea, 

 which inhabits the rivers of Africa, Ceylon, 

 and India, and is very rare. Under the epi- 

 dermis the shell is milk-white, stained with 

 violet near the base, and marked with rays also 

 of a violet colour. 



46. Cyprina. — Shell equivalve, inequila- 

 teral, obliquely heart-shaped, covered with a 



Gr 4 



