124 



oblong, irregularly sinuous at the margin on the sides, 

 with numerous extremely fine radiating striae only visible 

 towards the margin, the dorsal portion being sculptured 

 by numerous regular transverse ones ; hinge pointed, 

 terminal ; outside silvery, under the hinge a large 

 hollow vaulted chamber which is much curved on one 

 side and scaly on the outside ; perforation round and 

 nearly closed H. Torbay. 



A, TUBULARIS. Turt. B. p. 234. .F. p. 396. 

 Orbicular, whitish, with the beaks terminal ; perforation 

 entire all round and produced into a raised cylindrical 

 tube. i. Attached to Fuci. 



A. CORONATA. Bean in Mag. N. H. 8. p. 564. /. 

 52. Oval, glossy, pale amber, the upper valve concave, 

 smooth, with rather an undulating surface ; beaks 

 pointed, not terminal, above which are three or four 

 rows of spines the outer extending beyond the shell 

 giving it a coronated appearance ; under valve convex, 

 with an irregular surface and a few indistinct traces of 

 longitudinal striae. .... Scarborough. 



TRIBE. RUDIST^E. 



Ligament, if any, undiscovered, or represented by a 

 tendinous cord which attaches the shell. 



