124 CYPRINID.E. 



Its triangular form, smooth, glossy surface, and more especially 

 the small marginal tooth, at once distinguish it. In all our other 

 species the anterior margin is shortest and concave, and the lunula 

 deeply excavated ; but in this tlie posterior and anterior slopes are 

 equally direct from the very summit. 



It must be very closely assimilated to the Venus triangularis of 

 Montagu, the Cypriiia triangularis of Turton, in his " British Bi- 

 valves," Bnt I cannot make out the requisite number of teeth to 

 bring it within the genus Cyprina, or to correspond with their de- 

 scri|)tions. A hasty observer might confound it with the young of 

 Cijprina Islandica, which is more rounded and rough. 



The existence of a marginal tooth would, literally, exclude the 

 shell from this genus. But the general cliaracters will bring it nat- 

 urally into the same genus with A. castanea and sulcata. More- 

 over, a marginal tooth is more or less developed in individuals of 

 all the species ; and this only shows the close alliance of the genus 

 to Venus, with which, indeed, Blainville unites it. 



Astarte elliptica. 



Shell elongated, elliptical, beaks m<.»derati.'ly elevated, rather obtuse, sul^-cen- 

 tral ; anterior margin excavated and forming a pretty distinct angle at its junc- 

 tion with the ventral margin, which is but gently curved ; ligament margin nearly 

 straight, descending very gently, end rounded ; coarsely waved, the waves often 

 disappearing Ijelow ; hinge-margin delicate ; interior a dead sub-livid color ; mar- 

 gin simple, epidermis dark. 



Cms^hui ornta, Brown (not Smith). Edinb. Nat. and Geog. Sc. i. 12, pi. 1, figs. 8, 9. — 



Browv, 111. Conch. 96, pi. 38, fios. 12, 13. 

 Crasslna sulcata, Nils. Nov. Act. Holm. 187 (1822), ]>]. 2, figs. 1, 2. 

 Cmssina elliptica, Hanley, Recent Shells, Suppl. pi. 14, fig. 36. — Thorpe, Br. Mar. 



Conch. 246, fig. 107. — Brown, Conch. 111. 96, pi. 38, fig. 3. 

 Astarte elliptica, McGilliv. Moll. Aberd. 259. — Gray, Cat. Br. Mus. (Br. Moll.) 92.— 



Forbes and Hanl. Br. Moll. i. 4,59, pi. 30, fio-. 8. 

 Astarte semisulcala (not Leach), Moll. Ind. MdII. Gr<enl. 19. — Philippi, Abbild. ii. 



57 (Astarte), j.l. 1, fig. 10 — Loven, Ind. Moll. Scand. 37. 



Shell in most respects like A. sulcata. Its form is more elon- 

 gated, and of an elliptical rather than triangular outline, though 

 somewhat angular on account of the beaks and the slight excava- 

 tion of the anterior slope ; the beaks are a little in front of the 

 middle, and rather ol)tuse, 1)eing quite tumid and not compressed 

 near the a[)ex ; the hinge slope is much less rapid, in fact nearly 

 horizontal ; the hinder end is well rounded, rarely acute or trun- 

 cate ; dorsal excavations deep ; epidermis yellowish-brown (young) 



