ASTARTE. 465 



Crasdna comjyressa, Brit. Marino Conch, p. 00. 



Astnrtc multicostata, Macgill. (not Smith) Moll. Aberd. p. 260. — Phil. Neuer 

 Conchyl. vol. ii. p. 59, Astarte, pi. l,f. 8. 

 „ Banksii, Loven (not Leach nor Hanley) Index Mollusc Skandinavia;, p. 

 38 (from specimens). 



There are certain genera which apjDear to admit of a 

 much wider range of variation in their species, than others, 

 and pre-eminence in this respect may perhaps be claimed 

 for Astarte, so comparatively independent of form and 

 sculpture, do the true and permanent specific characters 

 in this genus appear to be. In diversity of variation, the 

 present species stands almost without a rival in its genus, 

 each locality, comparatively speaking, yielding its own 

 peculiar variety, yet so intimately connected by minute 

 gradations with the most apparently opposite examples, 

 that it seems utterly impossible that they can collectively 

 constitute more than a single species. 



We conceive the typical form to be subtrigonal, and 

 equally broad as long, either almost smooth, — excepting 

 always more or less obsolete costellse at the beaks, — or 

 much more usually entirely covered with most closely set 

 or crowded costellse, which are thirty in number at the few- 

 est, but more frequently forty, or even more, and are never 

 much elevated, the valves seeming as it were sulcated rather 

 than ribbed. The interstices are simple and narrow. The 

 valves are almost equilateral, and vary from comj^ressed to 

 ventricose, the ordinary rule being, that the more triangular 

 is the shell, the more ventricose will it be ; they are always 

 small, strong, opaque, and covered with a smooth more or 

 less glossy strongly attached yellowish epidermis. The 

 swell of the ventral margin ranges from simple convexity to 

 full arcuation, and the declination in the dorsal edges in- 

 creases in like proportion with the arcuation of the former, 

 yet typically is moderate and barely convex behind, but 



VOL. I. 3 o 



