THE GENUS CVTHEREA, OF LAMARCK. 



300 



A. concentrica, Venus concentrica, Ginel. 

 A. exoleta, Venus exoleta, Linn. V. lentiformis, Sow. 

 A. lincla, Venus lincta, Maton. Cylherea lincta, Lamk. 

 A. lupinus, Venus Iwpinus, Poli. Cylh. lunaris, Lamk. 

 A. variegata, V. exoleta variegata, Chemn. vii. f. 407, V. aus- 

 trale, Quoy. Vo. Astrol, t. 84, f. 

 Var. ? — Cyth. rufa, Lamk. 



A. juvenilis, V. juvenilis, Chemn. vii. f. 405. V. juvenilis, Gmel. 

 A. prostrata, Venus prostrata, Chemn. vi. f. 298. Venus exca- 

 vata, Gmel. Schroet. Eil., iii. 8, f. 10. China, J. R. Reeves. 

 Arthemis subrosea (Gray).— Yates' New Zealand, 309. 

 Arthemis ponderosa.— Shell orbicular, rather convex, very thick, 

 solid, heavy. Smooth, covered with a pale, yellowish periostraca ; 

 umbones and extremities concentrically grooved. Disk opake white ; 

 hinge margin very thick. Anterior tooth rudimentary. Lunule 

 deep, short. Like A. concentrica, but heavier, larger, and less 

 grooved. 



Arthemis tumida.— Shell suborbicular, convex, solid, rather pel- 

 lucid, white, with close, fine, regular, concentric, ridges, the alte- 

 rnate ones becoming rather broader on the hinder side. Lunate 

 short, cordate ; hinder slope rather short ; slightly curved. 

 Arthemis Bruguieri. — Ency. Method, t. 277, f- L 

 Shell suborbicular, compressed, thin, white, with rather close, 

 concentric ridges ; the alternate ones ending before they reach the 

 hinder slope ; the front and hinder ends of the larger ones laminar, 

 and forming teeth-like processes on the edge of the hinder slope. 

 Lunule small, cordate. 



Arthemis bilunulata.—Sheti. suborbicular, compressed, pale, whit- 

 ish, with obscure brown rays, and close, regular, concentric ridges, 

 which are slightly elevated at each end, and form a series of small 

 teeth on the edge of the hinder slope, and others on the edge of a large 

 lanceolate, lunule- like, smooth space, surrounding the small cordate 



lunule. 



Arthemis africana.—Shett orbicular, rather convex, thin, brown- 

 ish white, rather pellucid, with regular, close, very fine concentric 

 grooves. Lunule short, cordate ; inside brownish, polished.— Var. 

 —Thinner, nearly smooth striae, very fine. 



Inhabits coast of Africa — Capt. E. Owen, R.N. 



