113 



47. Rhombic, longer than broad, rounded below, trans- 

 parent, whitish with pale violet longitudinal interrupted 

 striae, very thin and brittle, obliquely truncate at the 

 top, with a few pale violet spots below; front margin 

 incurved. i...l. Scarborough. Probably the young 

 of the W. Indian species, which, when mature, is in- 

 ternally of a jet black. 



GENUS. AVICULA. 



Inequivalve, fragile, with the dorsal edge straight and 

 transverse, the extremities produced, the anterior 

 one caudiform ; left valve emarginate, with a sinus 

 or notch through which the beard passes ; hinge 

 linear with one tooth in each valve under the beaks ; 

 ligament linear and marginal placed in a long 

 narrow groove. 



A. HIRUNDO. Turt. B. p. 220. t. 16. /. 3,4. F. 

 p m 405. MYTILUS. H. Lin. 1159. D. p. 320. 

 Turt. D. p. 108 /. 7. An. Ch. f. 7U,5.?An A. 

 TARENTINA. ? Lam. Rather oblique, smooth or fur- 

 nished with a few scales about the margin, dull greenish 

 grey or brown with pale rays ; tail rather elongated ; 

 wing large and deep. Dublin Bay, Torbay and W. 

 Coasts, rare, up to 2. 



TRIBE. PECTINIDES. 



Ligament internal or semi-internal) shell for the most 



