﻿CYRENA.— I'l.ATE XVIII. 



Specie.s lOG. 



Cteena placida. C'l/r. I 

 pressd, altd, /a'n'ijul'i, 

 fere ifqiiilait'ivli, in. 

 rohmdia, 'iimlionihns de2rressis, oMtisisdinis. 



The placid Uyekna. Shell ovately rounded, com- 

 pressed, high, smooth, covered with a striated 

 epidermis, almost equilateral, pale rose within, 

 sides rounded ; umboes depre.ssed, very obtuse. 



Deshaye.s. Proc. Zool. Soc. 1854, p. ID. 



Hah. ? Cum. Coll. 



Species 11)7. (Alus. Brit.) 

 Ctrena notabilis. Ci/r. testa siibrhiimhi)ide<!, depressd, 

 stthcrmqiressd, tcnuiter driatd, ejiidermidt; tenuis- 



simd indidd ; latere antico hrevi, rotunda, infra 

 ninhones exoavato ; latere post ico ohlongo, arigu- 

 lato, j)ost angulum extus irdilsque purpurea, mar- 

 'fmc dorsali panlb derjivi, arciiato, maryine termi- 

 nal i late truncato. 



The remarkable Cyrena. Shell subrhomboidal, 

 depressed, rather compressed ; finely- striated, 

 covered with a very thiu epidermis ; anterior 

 side short, rounded, excavated under the umboes ; 

 posterior side oblong, angular, purple within 

 and without behind the angle, dorsal margin a 

 little sloped, arched, terminal inargia broadly 

 truncated. 



Deshayes. Proc. Zool. Soc. 18-">4, p. 21. 



Ihd,. Payti), Peru. 



Having much the form of a Cijpricardia. 



