C. D.p. 166. f. 18. T. JUGOSA. Brown in Wer. T. 

 2. p. 506. t. 24. /. 2. PETRICOJAOCHROLEUCA. 

 Lam. Oboval, tumid, and broader posteriorly, flex- 

 uous and produced anteriorly ; thin, brittle, white or 

 brownish with numerous thin raised unequal striae, 

 whose interstices ave minutely striated longitudinally j 

 teeth strong, elevated, two in one valve, a cloven tooth 

 in the other. l...lih Ireland, rare. 



P. POLYGONA. Turt. B. p. 96. F. p. 438. 

 TELLINA P. Mont. Sup. p. 27. t. 28. /. 4. Turt. C. 



D. p. 180. Somewhat orbicular, somewhat truncated 

 and angular at one end, rounded at the other, with fine 

 transverse striae and minute longitudinal ones, the mar- 

 gin uneven ; beaks not quite central ; in one valve two 

 large distant teeth, in the other a large cloven triangular 

 tooth and a small one near it. j...|. frith of Forth. 



P. LASKEYI. Turt. B. p. 89. F. p. 438. TEL* 

 LINA S. Mont. Sup. p. 28. t. 28. / 3. Oval-oblong, 

 smooth, glossy, slightly contracted anteriorly, purplish 

 white under a yellowish olive epidermis, rounded at one 

 end, obtusely pointed at the other: two approximate 

 sub-bifid teeth in one valve, a single tooth in the other. 

 0,40. . ., Frith of Forth. 



