31 



P. STRIATA. Lin. 1111. D. p. 37. Don. t. 117. - 

 Mont.26.Turt. B. 11. P. CLAVATA. Lam, 9. 

 P. NANUS. Ptefc. W.-Wood, G. C. t. 16./ 1, 2, 3, 

 4,8. Ch.f. 867, 8,9. 2teK?. . 24. / 2. Sow. . 

 /. 2. Transverse, conoid, posteriorly short, tumid and 

 rounded, anteriorly produced and subcom pressed ; 

 posterior area strongly reticulated by arched striae, 

 elsewhere slightly striated except a smooth triangular 

 space at the posterior ventral margin ; one large 

 rounded accessary plate over the hinge before which is 

 a lengthened one a third connects the ventral edges ; 

 apophysis long slender and curved. i...l. Ship's 

 timber. 



* * halves not divided by a groove. 



P. DACTYLUS. Lin. 1110. D. p. 35. Lam. 1. 



Mont. 2Q.Turt. B. 8.Ch. /. 859.-- Don. t. 118. 

 Sow. G. Reeve. 24. /. 1.^. 457. Transversely 

 elongated, beaked posteriorly and rounded anteriorly ; 

 with concentric waved muricated ridges and indistinct 

 radiating striae towards the beaks ; hinge margin re- 

 flected and supported by numerous small plates so as 

 to form quadrangular cells ; four accessary plates. 4 or 

 5. Common. 



P. CANDIDA. Lin. Ill [.Don. t 132. Mont. 24. 

 Twt.B. lQ.D.p,36.F. pA57.Lam. 3. Ch. 



