6 A. E. Verrill on the Mollusca of Europe and N. America. 
era, Argina and Scapharca, where several writers have placed 
them. 
He also states that Mactra ovalis isa variety of MM. solidissima. 
He may not have seen a specimen of the true ovalis, 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, and 
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 soli- 
dissima is abundant everywhere along our sandy shores to South 
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 per- 
fectly distinct from A. borealis. He reduces A. quadrans to a 
variety of A. castanea, and gives it a name that is quite uncalled 
for, even if this view were correct. He then makes A. Port- 
landica a variety of A. compressa; but I have already shown 
(Amer. Journ. of Science, April, 1872) that it is a variety of A. 
quadrans. His arrangement of the other species of Aséarte is 
equally objectionable, but it is not necessary to discuss them 
here. 
The Pecten fuscus Linsley is given as the young of P. trradi- 
ans, from which it is very distinct; but the writer has shown 
(Amer. Journ. of Science, vol. ii, p. 861, and vol. ii, p. 218, 
1871-72) that it is really the young of P. tenuicostatus. 
Dekay is given as the authority for dolis salmonacea and 4. 
gymnota ; but they were both described by Couthouy in 1888, 
from whom Dekay borrowed both the descriptions and figures, 
five years later. 
He states that Dentaliaum dentale (non Linn.) is a variety of 
Kntalis striolata, and that the latter is a variety of D. abyssorum 
Sars; but both of these statements are incorrect. The first is 
the Dentalium occidentale Stimpson, and is a true Dentaliwm, 
entirely different, generically and specifically, from the striolatu; 
and the latter is also quite distinet from abyssorwm. Possibly 
Mr. Jeffreys has not seen perfect specimens of all the American 
species ; otherwise, I cannot understand how he could have 
made these statements. 
He is correct in considering Crepidula glauca a variety of C. 
fornicata, as others have done before him; but he has adopted 
a serious mistake, made by several other writers, in regarding 
C. plana (or unguiformis) also as a variety of C. fornicata, from 
which it is really very distinct. It is a very common error to 
suppose that this species always inhabits the inside of dead uni- 
