A MANUAL OF AMERICAN LAND SHELLS. 13 



found the yellowish-green unicolored variety, once described as Helix 

 suhglohosa ; 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 uni- 

 form; in this respect also differing essentially 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 gardens and open 

 fields, but are generally confined to forests, sheltered under logs and 

 stones, and are rarely seen abroad except during twilight or on damp 

 and dark days; indeed, they almost entirely disappear as the forests 

 are cut down, and seem to flee the approach of man. The European 

 species, on the other hand, follow in the track of cultivation, and are 

 common in gardens and fields, on walls and hedges, and other places 

 exposed to the action of light. With the exception of Patula alter- 

 nata and Hemitrochus varians, Liguus fasciatus, &c., there is scarcely a 

 species having bands or variegated colors inhabiting eastern North 

 America; and even there these latter species can scarcely be regarded 

 as an exception, as they are only to be found at the southern part of 

 Florida, and are more properly West India shells. In Texas and be- 

 yond the Rocky Mountains in Oregon and California, many of the 

 species have one or more bands. 



Another peculiarity of the American snails is the tooth-like append- 

 ages with which the aperture of a large proportion of them is armed, 

 and which are characteristic of the group designated by Ferussac under 

 the name of Helicodonta. More than one-half of the whole number, and 

 more than three-fourths of those with reflected lips, are thus provided. 

 In some species these appendages assume the form of folds rather than 

 teeth; and in others we have simple threads or laminae revolving within 

 the aperture in the course of the spire. They are not formed until the 

 shell has attained its full growth. 



The genera not furnished with an external shell were grouped into 

 one family of Limacidce by Binuey, who thus describes their habits: 

 They are more especially nocturnal than the other families of the order, 

 and they are so rarely visible in the daytime that thousands may be 

 near without being known. The injury which they commit in kitchen- 

 gardens, for this reason, is often vaguely ascribed to worms or to birds, 

 and no measures are taken against the real culprits. Their habits, in 

 general, coincide with those which have been described as distinguish- 



