THE GENUS CYTHEREA, OF LAMARCK. 305 



Var. — Rather wedge-shaped ; more produced in front. Inhabits 

 Mexico. — Capt. W. Belcher. 



Trigona bicolor. — Shell trigonal, thin, white, pellucid. Hinder 

 slope purple. Inside iridescent. Inhabits coast of Africa. — Capt. 

 E. Owen, R.N. 



Trigona laevigata. — Shell ovate, trigonal, rather thin, pellucid, 

 pale fulvous, white varied, slightly concentrically wrinkled. 



Trigona angulifera (Cytherea trigonella, Lam., No. 28? — Shell 

 oblong, triangular, thin, pellucid, rather swollen, white, varied with 

 zig-zag concentric lines. Hinder slope purple. Internally purple 

 varied. 



Trigona tripla (Cytherea tripla, Lam., 12; Venus tripla, Linn., 

 Chemn., vi., f. 330-332. 



*** With a rudimentary rugose hinder tooth in the right valves. 

 Anterior tooth distinct. 



Trigona radiata, n. s. — Shell trigonal, rather compressed, solid, 

 reddish, with distinct darker zones and narrow white rays. 



Chione (Gray). 



Shell ovate, edge entire or crenulated. Hinder hinge tooth en- 

 tire, anterior lateral tooth short, conical, close. Syphonal inflection 

 moderate. 



Chione erycina (Cytherea erycina, Lan.) Cy. pectoralis, Lam., 

 is a variety. 



Ch. lilacina (Cyth. lilacina, Lam.) 



Ch. tortuosa (Cytherea tortuosa, Sow., Zool. Proc, Panama.} 



Ch. vulgaris (Venus Chione, Linn.) 



Ch. aurantia (Venus aurantia, Chenn.) 



Ch.pulchra (Venus pulchra, Gray, Wood, Suppl., f. 16. 



Ch. impar (Cytherea impar, Lamk., not Chenn.) 



Ch. Kingii (Venus Kingii, Gray, Wood, Suppl., t. 2, f . 9 ; Cyth. 

 citrina, Lamk. ?) 



Ch. albida (Venus albida, Gmel., List., t. 273, f. 109). 



Ch. Iseta (Venus lata, Chenn. vi., f. 353), 



Ch. sulcatiua (Cyth. sulcalina, Lam., Chemn. vi., f. 271-72). 



Ch. circinnata (Venus circinnata, Born., t. 4, f. 8 ; V. guineensis, 

 Gmel.) 



Ch. Dione (Venus Dione, Lin.) 



VOL. vni., no. xxiv. 39 



