470 A. EF. Verrill on the Mollusca of Europe and N. America. 
shores, and may be seen in many American collections; they 
the structure of the hinge is well known; for Dr. J. E. Gray 
many years ago established a new genus (Argina) for the latter, 
Moreover, the differences in the hinge, epidermis, and form are 
rewarkably constant; and, finally, the two species have the 
same geographical range from Cape Cod to South Carolina, and 
are often found together. Both are very common in Long 
hundreds of specimens of both species without. finding the 
slightest evidence in favor of Mr. J stents views. Indeed, they 
are only distantly related, and evidently belong to distinct gen- 
- Argina and ‘Scapharca, where several writers have placed 
them. 
He also states that Mactra ovalis isa variety of M. soldissima. 
He may not have seen a specimen of the true oval’s, for it is not 
common in collections; but the genuine ovalis is certainly a 
very well-marked species, widely different from the solidissima. 
They differ greatly in the hinge, epidermis, form of shell, an 
position of the umbos; moreover, the animals are also quite dif _ 
ferent. Both occur together of equal size in the Bay of Fundy; 
but the former is not known south of Cape Cod, while the so’ 
disstma is abundant everywhere along our sandy shores to Sout 
- Carolina. : 
Concerning Astarte castanea he says, ‘Perhaps a variety of 
A. borealis Ch. ;” but castanea is one of the best-defined species 
in this difficult genus, varies comparatively little, and does not 
extend far north, its range being decidedly southern. It is pet 
ectly distinct from A. borealis. He reduces A. quadrans to 4 
; y of A and gives ita — that is quite uncalled 
, even if this view were correct. He then makes A. Port 
