95 

 * Ribs spinous or tuberculated. 



C, AcuLEATUM.Zm. 1122 D. p. 115 Lam. 14 

 E.M. t. 297. / 5 Ch. f. 157 Pen. 4. p. 187. t. 

 53. / 1 -Don. t. bMont. p. 77 Lin. T. S.p. 62 

 Wood. G. C.p. 207. t. 51. / 1 Turt. C. D,p. 28 

 Turt. B.p. 181. *. 13. / 6, 1F. p. 420 (Young, 

 C. SPINOSUM. Sow. Brit. Mis. t. 32) Very tumid, 

 comparatively light, obliqae, subangulated anteriorly ; 

 with about twenty-one ribs armed anteriorly with long 

 sharp spines (lancet-shaped but round in the old shells) 

 posteriorly with rather flattened obtuse tubercle, trans- 

 verse striae only in the interstices of the ribs. 4. W. 

 Coasts. 



C. TUBERCULATUM. Lin. 1122 D. p. Ill Lam. 

 15 Pen. 4.p. 88 Don. t. 107. f. 10 Mont. p. 568. 

 Lin. T.S.p. 64 Wood. G. C.p. 210. t. 50. f. 1, 2 

 Dor. Cat. p. 31. t.2. f. 2. Turt. D. p. 28. /. 

 12. Turt. B. p. 183. .F. p. 421. Subglobular, 

 ponderous, a little truncated anteriorly, with twenty- 

 one ribs anned anteriorly with tubercles, posteriorly 

 with scaly plates; pale chesnut usually with darker 

 zones, the transverse wrinkles crossing the ribs. 4. 

 W. Coasts. 



