HELIX. 87 



spcct, from the snails of Europe. It is true that in 

 localities favorable for their residence they may be col- 

 lected in considerable numbers ; and especially is this 

 the case in the States north of the Ohio river. But 

 even there, they seem to live independently of each 

 other, and not to unite into herds or communities. 

 There are occasional exceptions however, as in the case 

 of H. alternata, very large numbers of which have been 

 observed collected into a small space, especially in win- 

 ter, as if for the purpose of imparting warmth to each 

 other. The few species of European snails which have 

 been introduced retain their native habits. IT. Jiortensis 

 for instance, which has been transplanted to some of the 

 small islands in the vicinity of Cape Ann, is found there 

 in countless numbers, literally covering the soil and 

 shrubs. It is worthy of notice also, that each island is 

 inhabited by a variety peculiar to itself, showing that 

 the variety which happened to be introduced there has 

 propagated itself, without a tendency to run into other 

 variations. Thus, on one islet we have the yellowish 

 green, uni-colored variety, once described as If. subylo- 

 bosa; and on another, within a very short distance, we 

 find a banded variety, and none others. 



In regard to colors, our snails are quite plain and 

 exceedingly uniform ; in this respect also, differing essen- 

 tially from the species of the old world. They vary 

 from yellowish-green through horn-color to chestnut, most 

 of them being simply horn-colored. This is perhaps 

 owing to the fact that our species do not infest our gar- 



