614 



6. Cyther^a tripla (pi. cxxviii. f. 18, 19, 20, 21, 22), 

 Linn., Mantis, p. 545 ; Lamarck, no. 12 ; Chemn. f. 330, 331. 



Cyth. testa trigona, crassa, alta, pallide fulva vel aurantiaca, 

 nonnunquam fasciis violaceis radiata, iutus plermnqne purpm-ea ; 

 margine ventrali subrecta, lateribus excavatis ; area postica angu- 

 lata, magna, cordiformi ; area antica magna, subangulatfi ; lunula 

 distincta. 



Shell trigonal, tliick, deeper than long, of a pale buff or orange- 

 colour, sometimes rayed with purple bands, sometimes deep purple 

 within. There is a peculiar swell in the disc of the shell near the 

 umbones, then the angle is contracted, and again spreads broadly 

 at the ventral margin. Both sides present large cordiform areas, 

 and the lunule is defined by an impressed line. The spreading of 

 the ventral margin does not take place till the shell is full grown. 



Senegal. 



7. Cyther^a corbicula (pi. cxxviii. f. 37, 38, 39), La- 

 marcJc, Anim. s. vert., sp. 11. 



Cyth. testa ventricosa, alta, subtrigona; latere autico subro- 

 tundato, latere postico subcoarctato ; umbonibus magnis, sub- 

 centralibus; colore palHde luteo, fasciis castaneis radiato, vel 

 omniuo castaneo, iutiis albo. 



Shell very ventricose, trigonal, with large umbones, and nearly 

 as high as broad ; the hinder side almost narrowed to a point, the 

 front side round. The specimens (f. 39) from CaUfornia, in 

 Mr. Sowerby's collection, are pale, with duU-brown rays and dull- 

 brown epidermis. The specimen (f. 38) in Mr. Gubba's collec- 

 tion has the rays much brighter. Mr. Cuming has one of a 

 chestnut-colour aU over. 



Island of Margarita, West Indies. 



8. CytherjEa Hindsii (pi. cxxviii. f. 27), Kanley, Sp. of 

 SheUs. Wood, Suppl. pi. 15. f. 35. 



Cyth. testa C. radiata simih, sed altiore ; latere postico brevi- 

 usculo; umbonibus inflatis; lunula et area postica latis, indis- 

 tinctis, fascia castanea circumscriptis ; colore paUide fulvo, fusco 

 fasciato et angulatim Hneato ; epidermide velutina. 



Shell shorter and more inflated than either C. corbicida or 

 C. radiata, the hinder side much shorter than in the former. 

 Instead of a smooth greenish-brown epidermis, it has a velvety 

 coating, as in C. argentina. 



The specimen figured is from Guayaquil Bay. Mus. Cuming, 



