20 LAND AND FRESH WATER MOLLUSKS 



cation of species so derived. Usually, however, there is no 

 particular reason for doubting the accuracy of these identifica- 

 tions. It has not seemed necessary, in most cases, to cite the 

 authority for the locality, a course which would have unduly 

 increased the bulk and diminished the clearness of the distribu- 

 tional statement. The authority, as a rule, can easily be found 

 by reference to the bibliography. In a few cases, however, it 

 has seemed desirable to include in parentheses the authority for 

 the locality cited, especially when the latter seemed unusual or 

 debatable. 



Family HELICnXE. 



Genus Helix (L.) Pilsbry. 



Helix (Cepaea) hortensis Miiller. 



Helix hortensis Muller, Verm. Terr, et Fluv., n, p. 52, 1774. — Binney, 

 Land and Fw. Sh. N. Am., 1, p. 181, figs. 317-320, 1869. 



Helix subglobosa Binney, Boston Journ. Nat. Hist., 1, p. 485, pi. xvi, 

 1867. 



Range. — Europe from Hungary to the Atlantic between middle 

 Scandinavia and the Pyrenees, northeastern border of North America. 

 Labrador ; Newfoundland ; Anticosti Island ! Barachois, Gaspe ; 

 Cape Breton Island ! 1 Halifax ! Casco Bay, Maine ! shore of Cape Ann 

 and adjacent islets, Mass. ! Nantucket Island ! Pleistocene deposits 

 near Portland, Maine ! 



A single specimen was once found in Greenland, but was doubtless 

 imported accidentally. The prevalent type is light yellow, without or 

 with only faint traces of bands. The former is Binney's H. subglobosa. 

 The wide distribution of the species, often on un- 

 inhabitable islets off a coast little frequented, and its 

 presence, which I have verified, in the glacial Pleis- 

 tocene of Maine, tend to confirm the view that it is 

 a prehistoric immigrant if an immigrant at all. 

 Fig. 1. Helix I have seen most of the commoner varieties which 

 hortensis var. are prevalent in Europe, but it is obvious to the col- 

 subglobosa Bin- kctor ^ tfae brighter co i ore d types with sharply 



define ddark bands form an insignificant proportion 

 of the American specimens ; while the shells as a whole seem smaller 

 than the average dimensions of European specimens. 



1 The exclamation point indicates that specimens from this locality have been 

 seen by me and verified as correctly identified. 



