46 PHILOSOPHY OF 2OOLOGT. 



the torpid species are numerous, and their habits have bean 

 studied with the greatest attention, as the marmot, the ham- 

 ster, and the dormouse. 



The food of these animals is very different, according 

 to the orders or genera to which they belong. The bats 

 support themselves by catching insects, and those chiefly of 

 the lepidopterous kinds ; the hedgehog lives on worms and 

 snails ; while others, as the marmot and hamster, feed on 

 roots, seeds, and herbs. They are nearly all nocturnal, 

 or crepuscular feeders. 



It is usually supposed that torpid animals are confined 

 to the cold regions of the earth. That they abound in such 

 regions must be admitted ; but their range of latitude does 

 not appear to be so limited as to prevent their occurrence 

 in warm countries. Thus the Dipus sagitta, is equally 

 torpid during the winter months in Egypt as in Siberia, 

 In the former country it is more easily revived by a very 

 slight increase of temperature, its lethargy not being so pro- 

 found. The tanric (Centenes caudatus), which is an inha- 

 bitant of India and Madagascar, becomes torpid even in 

 those countries, and continues so during nearly six months 

 of the year. 



The precise period of the year in which these animals 

 retire to their winter quarters and become torpid, has not 

 been ascertained with any degree of precision. The jump- 

 ing mouse of Canada (Gerbillus Canadensis) is said to en- 

 ter its torpid state in September, and to be again restored 

 to activity in the month of May. The torpid animals of 

 this country usually retire in October, and reappear in 

 April. It appears probable, however, that the different 

 species do not all retire at the same time, but, like the mi- 

 grating birds, perform their movements at separate periods. 

 It is also probable, that the time of retirement of each spe- 

 cies varies according to the mildness or severity of the sea- 



