43 



Pubescens by the large oval projecting teeth, which 

 extend forwards and have no lateral attachment. 



A. PRETENUIS. Turt. B. p. 48. t. 4. /. 4. MYA. 

 P.Pen. .p. 160. t. 50. f. 1. Mont. p. 41. Lin. t. 

 8. p. 37. Don. t. US Wood. G. C. p. 94. t. 24. /. 

 7, 8, 9. Dor. C. t. 4. f. 7. Turt. C. D. p. 101. 

 AMPHIDESMA. P. F. p. 432. Oval, flat, narrower 

 rounded and open anteriorly, posteriorly slightly 

 shorter and rounded, rough, white ; teeth oval and pro- 

 jecting. 1. ..li. Torbay. Distinguished from Declvisi 

 by the rounded anterior extremity. 



A. DISTORTA. Turt. B. p. 48. t. 4. /. 5. MYA. 

 D. Mont. p. 42. t. I./. \.-Pen. 4. p. 161. Lin. T. 

 S.p.[37.TTood. G. C.p. 98. D. p. 45. Turt. C. 

 D.p. 101. AMPHIDESMA. D. F. p. 432. Convex, 

 variously shaped, nearly closed, the margin generally 

 indented and the teeth rounded and projecting inwards. 

 1. Torbay. 



A. ARCTICA. Turt. B. p. 49. t. 4. /. 7, 8, MYA. 

 ARCTICA. Lin. 1113? Oblong, convex, posteriorly 

 truncated, anteriorly with two transverse ridges, one 

 along the hack margin, the other running obliquely to 

 the angle of the front margin ; beaks terminal, posterior, 



