10 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



tions and habits. So entire is the cessation of the function of respira- 

 tion, that the air contained between the epiphragm and the animal is 

 found to be unchanged. The circulation, however, may be partially 

 restored by a small degree of heat, the warmth of the hand being suffi- 

 cient to stimulate the heart to action. 



The snails pass the greater part of their lives under dead leaves and 

 logs, under stones, or burrowing in the ground. They seldom come 

 from their lurking-places while the sun shines, and indeed are never seen 

 ranging in the daytime unless the day be damp and dark. Should they 

 then be surprised by the appearance of the sun, they immediately take 

 shelter from its rays, under some cover or on the shaded side of the 

 trunks of trees. 



Their natural food is vegetable ; and the formation of the mouth and 

 the organs with which it is armed seems to be peculiarly well adapted 

 for cutting fruits and the succulent leaves of plants. The lower edge of 

 the jaw being applied against the substance to be eaten, the semilunar 

 rough instrument, which has been called the lingual membrane, is 

 brought up against it, cutting out and carrying into the mouth semi- 

 circular portions of nutriment. This operation is carried on with great 

 rapidity, and the substance to be eaten soon disappears. It is certain, 

 however, that some species l are also fond of animal food, and sometimes 

 prey upon earthworms, their own eggs, and even upon each other ; but 

 the slowness of their motions and their consequent inability to pursue 

 prey forbids the idea of their being dependent on animal food. They, 

 in their turn, become the prey of various birds and reptiles ; and it 

 is no uncommon thing to observe, in the forest, clusters of broken 

 shells lying on logs or stones which have been chosen by birds as con- 

 venient places for breaking the shell and extracting the animal. 



The snails of the United States are for the most part solitary in their 

 habits, differing very much, in this respect, from the snails of Europe. 

 It is true that in localities favorable for their residence they may be 

 collected in considerable numbers ; and especially is this the case in the 

 States north of the Ohio River. But even there they seem to live inde- 

 pendently of each other, and not to unite into herds or communities. 

 There are occasional exceptions, however, as in the case of Patula alter- 

 nata, very large numbers of which have been observed collected into a 

 small space, especially in winter, as if for the purpose of imparting 

 warmth to each other. The few species of European snails which have 



These are characterized by the lingual dentition. See Glandina. 



