TRIBE CONCHACEA. 95 



13.— Ch.f. 327, 8, 9.—E. *.250./. 1.— Reeve, t. 6\.— W.t. 7.f 

 48. Sub-equilateral, sub-triangular, ponderous, tumid at the elevated 

 beaks, slopes concave, sub-rostrated, the ventral edge being slightly 

 incurved anteriorly : cuticle olive, sometimes with dark narrow rays, 

 smooth, shining : inside white. 3.— Africa. {Sierra Leone.) 



Section. — Marine. 

 Usually destitute of lateral teeth. 



CYPRINA. 



Shell equivalve, inequilateral, obliquely heart-shaped, beaks ob- 

 liquely bent ; Uintje with three unequal teeth, approximate at the 

 base, and slightly divergent above ; lateral tooth remote, anterior, 

 (sometimes obsolete) ; ligament external, and partly sunk be- 

 tween the beaks. 



C. Islandica.* Lam. 2.—Turt. B.p. 135.—BI. t. 70. bisf. 

 5. — Sow. G. — Reeve, t. 65. — Venus I. Lin. 1131.— Z>. p. 176. 

 — -List. t. 272. f 108.— IF. t. 7 . f. 41.— Ch.f. 341.— Don. t. 3. 

 f. 77. Obliquely heart-shaped, thick, ponderous, white, under a 

 coarse, brown, rather glossy cuticle, and striated irregularly and 

 concentrically ; beaks prominent, lunule obliterated : inside white, 

 and the margins very entire. 3^..3f. — N. Europe and N. Am- 

 erica. 2 



C. Triangularis. Turt. B. p. 136. t. 11./. 19, 20. Venus 

 T. Mont. p. 577. t. 17./. 3.— D. p. 173.— W. t.7.f.35.~ 

 Turt. B.p. 238. Roundish with a triangular outline towards the 

 beaks, which are produced and equally sloping on both sides, 

 smooth, white : lunule lanceolate : three teeth and a curved lateral 

 in one valve, two and a lateral in the other, palleal scar not sinu- 

 lated. \. — England and Ireland. 



\ C. Minima. Turt. B. p. 137.— Venus M. Mont. p. 121. t. 

 3.f.3.-B.p. 166.— Turt. B.p. 236.— W.t. 7. / 17. Rounded, 

 with a triangular outline towards the beaks, compressed, with indi- 

 stinct smooth narrow transverse ribs ; lurid flesh-coloured, speckled 

 with minute livid dots, and when young the markings consist of 

 four longitudinal rufous spots, two near the beaks, two at the mar- 

 gin ; these by age become obsolete ; beaks posterior, much recurved, 

 the lunule lanceolate : inside white, sometimes with purple under 

 the umbones, margin entire. \. . \. — Guernsey. 



CYTHEREA. 



Equivalve, inequilateral, sub -orbicular, trigonal or transverse; 

 right valve with four primary teeth, of which three are divergent 



2 C. Tenuistria (Lam. 6.) is a Venus Chinensis. 



