396 MOLLUSCA. OSTREADiE. Anomia. 



Tart. Linn. iv. 288. — A. cymbiformis, Maton and liackett, Linn. Trans, 

 viii. 104. t. iii. f. 6. Mont. Test. Brit. Sup. 64 — A. cylin. Turt. Biv. 

 Brit. 232 — On fuci and sertularise. 



Length about half an inch, breadth a quarter, narroAver towards the beak, 

 which curves over the under valve, and ends in an obtuse point ; sometimes 

 smooth, but usually with some rough transverse marks, but no longitudinal 

 ones. 



396. A. striolata. — Shell oval, somewhat cylindrically con- 

 vex, and striate longitudinally, with the beak curved backwards. 



Turt. Biv. Brit. 233 — Roots of fuci. 



Resembles the last, but is marked with fine, rather remote, longitudinal 

 raised lines. 



397. A. aculeata. — Shell orbicular, with numerous longitudi- 

 nal prickly striae. 



Mont. Test. Brit. 157- t. iv. f. 5. Turt. Biv. Brit. 233 — On fuci and 

 among rocks. 



Diameter about half an inch ; depressed, whitish prickles ; rounded above, 

 concave, and somewhat concentrically disposed by the lines of growth ; under 

 valve wrinkled concentrically ; seldom prickly. 



398. A. fornicata. — Shell somewhat orbicular, and finely 



striate, the upper valve furnished with a vaulted chamber on the 



inside, under the beak. 



Lamk. Syst. vi. 228. Turt. Biv. Brit. 234. t. xviii. f. 12, 13 — From Tor- 

 bay, Dr Turton. 



Diameter about half an inch ; flat, white, margin sinuous ; longitudinal 

 striae towards the margin, and fine regular transverse ones towards the point- 

 ed beak ; inside silvery ; under the hinge is a large vaulted chamber, which, 

 on one side, is much curved, and scaly on the outside ; perforation of the un- 

 der valve round, and nearly closed. 



399. A. tubular is. — " Shell orbicular, with the perforation of 

 the under valve entire, and forming a cylindrical tube."" 



Turt. Biv. Brit, ccxxxiv — On fuci. 

 Shell about a quarter of an inch in diameter ; whitish, with the beak ter- 

 minal ; the under valve has the perforation entire all round, and produced 

 into a raised cylindrical tube ; the plug of attachment is tendinous." 



It is probable that several of the preceding shells may yet be reduced to the 

 rank of varieties. In the mean time, we have followed the arrangement of 

 Dr Turton. 



EXTINCT SPECIES. 



1. A. lineata Suborbicular, convex; when old, contracted towards the 



beak ; longitudinally striated ; perforation of the lower valve circumscribed. 

 — Sower. Min. Conch, t. ccccxxv. — In London Clay. 



