30 CARDIAD^. 



Moll. Sicil. vol. i. p. 51, and vol. ii. p. 33. — Hanl. Recent 

 Shells, p. 135. — Reeve, Conch. Iconica, Cardium, pi. 21, f. 

 121. 



Although Gmehn's name, exiguum, is prior to that of 

 Donovan, yet as his species was merely constructed from 

 the figure in Lister, and inadequately defined, it has no 

 just claim to precedence. 



There is a something so marked in the general outline and 

 moulding of this peculiarly angulated cockle, that a hasty 

 glance at even a worn and discoloured valve will enable us 

 to discriminate it from its British congeners. 



The contour is rhomboidal, with the hinder dorsal edge 

 so extremely short, that, excluding the umbones, the shape 

 may be termed triangular. The hinder dorsal area, which 

 is broad and abruptly flattened, is defined in fi-ont by the 

 extremely oblique and sharply-angulated umbonal ridge, at 

 which point is the greatest tumidity of the valves, which, 

 gradually decreasing in convexity, become compressed at 

 the anterior extremity. The external surface is destitute of 

 lustre, and of a white, or dirty- whitish hue, marked occa- 

 sionally with interrupted irregular bands of brownish rufous 

 spots, which are more perceptible towards and upon the 

 umbonal ridge. Although the shell is small, its texture 

 nevertheless is solid and opaque ; the entire area is occupied 

 by from twenty to twenty-two radiating ribs, which are 

 rather broad, not much elevated, and divided from each 

 other by distinct sulci, which become much wider at the 

 hinder extremity. These interstitial sulci are concentrically 

 punctated with impressed dots or lines, and the ribs them- 

 selves are armed with close-set coarse roundish nodules, 

 which in the young pervade the entire surface, but in the 

 more asred individuals are confined to the front of the shell 

 and the portion bordering upon the ventral margin, the re- 



