﻿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 is a variety of M. 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 eveiyw^here along our sandy shores to South 

 Carolina. 



Concerning Astarte castanea he says, " Perhaps a variety of 

 ^■1. 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. borecdis. He reduces ^-1. 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 Astarte is 

 equally objectionable, but it is not necessary to discuss them 

 here. 



The Pecten fiiscus Linsley is given as the young of P. irradi- 

 ans, from which it is very distinct ; but the writer has shown 

 (Amer. Journ. of Science, vol. ii, p. 361, and vol. iii, p. 213, 

 1871-72) that it is really the young of P. ienuicostatus. 



Dekay is given as the authority for ^Eolis salmonacea and ^. 

 gymnota ; but they were both described by Couthouy in 1838, 

 from whom Dekay borrowed both the descriptions and figures, 

 five years later. 



He states that Dentalinm dentale (non Linn.) is a variety of 

 Entcdis striolata, and that the latter is a variety of D. abyssoruyn 

 Sars; but both of these statements are incorrect. The first is 

 the Dentalium occidentale Stimpson, and is a true Dentalium, 

 entirely different, generically and specifically, from the striolata; 

 and the latter is also quite distinct from abyssorum. 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 vanety 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- 



