105 
and numerous sharp pointed lateral comh-like teeth ; 
ligament internal. 
* Margin crenulated. 
N, Nuctevs. Turt. B.p. 176. t. 13. f. 4.—F. p. 
401.—Arca. N. Inn. 1143.—Pen. 4. p. 217.—Don. 
2. t. 63.—Mont. p. 141.—Lin. T. 8. p. 95.— Dor. 
Cat. p. 37. t.12.f 6.—D. p. 244.—Turt. D. p. 8.— 
Da Cos. t. 65. f. 62. (rt. hand.) Ch. f.,574.—N. Mar- 
GARITACEA. Lam. 6.—Obliquely subcordiform, subtri- 
angular, anteriorly produced, cuticle blackish or dark 
olive green, (at times with yellowish rays and very 
minute striz) glossy; lunule oval; inside silvery, teeth: 
about twenty anteriorly, about ten posteriorly ; margin 
crenated. 0,40...2. Common. 
N. Tenuts. Turt. B. p. 177.—F. p. 402.— Arca. 
T. Mont. Sup. p. 56. ¢. 29. f. 1.—Pen. 4. p. 218.— 
D. p. 246.—Turt. D. p. 11. -. Obliquely-heart-shaped, 
roundish and nearly smooth, produced and rounded 
anteriorly, white or covered with a thin olive skin ; 
inside white, a little pearly, margin entire. 4...3. 
Scotland. 
N. Rosrrara, Turt. B. p. 173.—F. p. 402.— 
K 3 
