426 VENERIDiE. 



A West Indian shell ; introduced, ivithout any specified locality, 

 by Da Costa (who became aware of his error after 'publication), 

 from merely having seen it, in a collector s cabinet, as a British 

 production. 



We have appended as a note to the Veneres the original description (from 

 whence all the others have been aljridged) of the Venus subrhomhoidea of Alontagu, 

 not because Ave consider it a true Venus (for that, at least, the bidentate hinge 

 will certify), but solely from the extreme uncertainty of its actual generic posi- 

 tion, which, if determined without examination of the original specimen, must, 

 of course, be conjectural. Had the Vcncrupis Irus been found so far north, our sus- 

 picions would certainly have inclined to the supposition that it was only a dis- 

 torted individual of that species, with the hinge imperfectly developed ; and 

 our inference from the language of Montagu (we may remark, by the bye, that 

 he uses the word " behind," in the above description, in a different sense from 

 his usual one, as the figure — which evidently represents a distorted and probably 

 lithodomous shell — shews the replication to be on that side usually called the 

 anterior or front one, by the writers of the Linnean school,) would rather have 

 led to our placing it with Fetricola, than, as Turton has done, with Asiurte, the 

 large pallicil sinus forbidding its admission into the latter genus : — 



Venus subrhomhoidea, MoNT. Test. Brit. Suppl. p. 49, pi. 28, f. 2. — Turt. Conch. 



Diction, p. 24 G. — Flem. Brit. Anim. p. 448. 

 Crassina , Turt. Dithyra Brit. p. 129. 



" Shell subrhomboidal, rounded at one end, truncated at the other, and irregu- 

 larly wrinkled concentricallj', especially towards the margin, where the ridges are 

 prominent but obtuse ; these are decussated by extremely fine approximate longi- 

 tudinal strife ; umbo small and nearly central, but the beak reclines to one side ; the 

 colour is white, with a tinge of rufous at the truncated end. The inside is white, 

 with a dash of purple at that part which is rufous on the outside ; the margin is 

 plain ; cicatrix broad, spreading half across the shell : the hinge is singularly 

 formed ; in each valve care two strong, plain teeth, one of which stands very 

 oblique ; behind these the margin projects inward, and then doubling back, forms 

 a smooth replication and a cavity between it and the exterior edge of the shell 

 behind the umbo for the connecting cartilage. Length half an inch ; breadth 

 three-quarters." 



" A single specimen (in a living state) is recorded to have been dredged by 

 Mr. Laskey off St. Abb's Head, in the Frith of Forth. It bore the most marked 

 resemblance to Venerupis Irus, but differed in the closeness of its striae, the 

 absence of thin membranaceous ridges, the replication of the hinge margin, and 

 by its dentition exhibiting only two simple teeth in each valve." 



