96 CLASS MAMMALIA. 



This is sufficient to prove the prodigious dominating influ- 

 ence of this organ over the general structure of the animal. 

 The majority of the bats live on insects. Their stomach 

 is simple without thread or complication. The intestinal 

 canal is short and of a diameter pretty equal throughout, 

 and the caecum is entirely wanting. The teeth correspond 

 with this arrangement. The incisives are lobular, the ca- 

 nines long and sharp, and the molars bristling with points. 

 Some bats (the Roussettes), which live principally on fruits, 

 vary a little in the conformation of the teeth and intestines, 

 and are also characterized by a lesser prolongation of the 

 dermis : accordingly, it is with some difficulty that we con- 

 cede to them the name of bats at all. 



The sharp teeth of most of them are the only weapons 

 with which nature has provided them to attack, seize, and 

 lacerate those insects which form their subsistence. For, 

 catching them in their flight, they possess one facility 

 which has not been very generally remarked. This consists 

 in the largeness of their mouths. 



The opening of the lips in the mammiferous animals in 

 general does not extend beyond the canine teeth. We would 

 be almost inclined to assert that the upper lip followed the 

 lot of the intermaxiliaries ; that it was subordinate to them, 

 and formed as it were their natural covering. In fact, the 

 mouth is never large, and deeply cut, except in those 

 animals which possess very long intermaxiliaries ; and on the 

 other hand, is always extremely narrow where these bones 

 are small. To this rule, however, the bats, at least those 

 of them which are insectivorous, form a remarkable, and, 

 we believe, a solitary exception. The commissure of their 

 lips is prolonged considerably behind and corresponds with 

 the last molar but one. Their cheek-pouches may be re- 

 garded as the cause of this anomaly. The cheeks, which 

 are rendered flabby by these appendages, unfold and extend 

 with the lips, and the lower jaw is thus capable of being so 



