424 VENERIDiE. 



in the event of others not coinciding with our views of its affilia- 

 tion, we shall, at least, have enabled them more readily to com- 

 prehend what was intended by Montagu, by redescribing the 

 species from the original type (which is sadly broken), and its 

 exact but perfect facsimiles from the coast of the West Indian 

 Islands. The epithet radiata was bestowed on the species, 

 through the presence of a character in the described individual, 

 which is rather exceptional than constant. 



Somewhat ovately cordate, solid, opaque, not particularly in- 

 equilateral (the front being at least half the length of the hinder 

 side), rather dull, more or less ventricose, profundity rather less 

 in front : exterior whitish, adorned with thin, short, concentric 

 lamellae, which are rendered wavy by the very closely disposed 

 simple radiating interstitial costellre, and become extremely 

 crowded near the lower edge, but are less so in the very young, 

 and upon the umbonal region of the adult. Ventral margin more 

 or less subarcuated, a little flattened in the middle. Anterior 

 side tapering to a rounded extremity ; the declination of the 

 upper edge (which is straightish near the beaks) moderate, but 

 not equal to the rise of the lower margin. Hinder dorsal edge 

 moderately sloping, and not very convex ; hinder termination 

 attenuated, subaugulated in the middle. Ligament small. Um- 

 bones rather prominent ; beaks acute, leaning forward, and pre- 

 ceded by a large cordate lunule, which is well defined by a 

 groove, but not much sunken nor yet smooth, possessing, though 

 obscurely, the general sculpture Hinder dorsal area large, deeply 

 and equally excavated in either valve, but remotely cross-barred 

 with chocolate colour in the left valve only. Inside white, or 

 tinged on the disk with flesh-colour; hinge-margin broadish, 

 stained with purplish chocolate behind. Front and lower edges 

 crenated within. 



Introduced as British tvith doicbt by Montagu, who had taken 

 a single valve from the sand of Falmouth harbour. It is a native 

 of the West Indies and of the shores of Central America. 



