﻿A. E. Verrill on the Mollusca of Europe and N. America. 7 



valve shells ; for it very often occurs on the outside of such 

 shells, on stones, the back of Limidas, &c,, and is frequently 

 associated intimately yviili/ornicata in all these situations ; but 

 nevertheless it always retains its essential characters, under all 

 circumstances. The typical fornicata is also often found with 

 it, plentifully, on the inside of dead shells. 



Nor can Margarita acuminata be the young of M. varicosa ; 

 for in our collection there are full-grown specimens of both, 

 equal in size, from Labrador. 



There is no sufficient reason for adopting the name Lacuna 

 divaricata in place of L. vincta ; for it is not the Trochus divari- 

 catus of Linne (1767), although it is the shell described under 

 the same name by Fabricius in 1780, as shown long ago by Dr. 

 Stimpsou and others. Fabricius made a mistake which we 

 have no right to perpetuate; nor does "usage," to which Mr. 

 Jeffreys so often appeals, sanction the change. 



The Lunatia triseriata is not, as Mr. Jeffreys thinks, the 

 young of L. heros, but only a color-variety, as the writer had 

 previously shown (April, 1872). Both varieties occur together, 

 from the smallest to the largest sizes ; but the former some- 

 times becomes plain colored before reaching maturity. There 

 is no evidence that Natica clausa is the Nerita affinis of Gmelin, 

 but quite the contrary ; for the latter was placed in the section 

 of umhUicated species, was described as sUvery within^ and came 

 from New Zealand ! It is probably one of the Trochidae, and 

 certainly could not have been this imiierforate Natica. 



In this place I shall not enter into a discussion of the numer- 

 ous cases in which the author has reduced the American shells 

 to " varieties" of the European species, because in many of 

 these cases there must long be great diversity of opinion, and 

 for most purposes it matters little whether these closely related 

 forms be called "varieties" or "species," so long as the actual 

 differences are recognized. But since Mr. Jeffreys has evidently 

 made so many important mistakes in his article in regard to 

 the identity of species, and has united those that have no near 

 affinities, as already shown, it is logical to conclude that he 

 may have made other mistakes in the case of more critical 

 species. He must therefore pardon us if we regard his decisions 

 in all these cases as at least doubtful, until confirmed by other 

 evidence. 



