116 CLASS MAMMALIA. 



which are easily recognised by the surrounding membranes 

 of the nose. 



The first may be considered as bats, upon the very slen- 

 derest claims. The general tendency to augmentation in 

 the cutaneous system is carried on by them only in the 

 wings. No other part is similarly developed. There is no 

 volume in the tragus forming a second ear, no'tunnels about 

 the nostrils, no interfemoral membrane. There are but 

 some trifling vestiges of the latter, extending along the in- 

 ternal edges of the legs. 



It is far otherwise, however, with those bats which de- 

 stroyed the first establishments of the Europeans in the New 

 World. They are buried as it were, and lost amid the mul- 

 tiplied foldings of their integuments. Their ears are simple 

 and double, and their nostrils surrounded with leaves and 

 bordered with semicircular crests. Their interfemoral 

 membrane occupies the entire space comprehended between 

 their legs, which are themselves of very remarkable dimen- 

 sions. This augmentation is visible also in the membrane 

 of the wings, the size of which is considerably increased by 

 an additional phalanx on the third finger. The body of the 

 animal itself is scarcely to be distinguished amidst all this 

 integumentary profusion. Their appearance is thus ren- 

 dered more gloomy, and their physiognomy more ferocious. 

 There is something vague and indefinite about their forms, 

 which aggravates the horror which the remembrance of their 

 devastations has inspired. 



What is most remarkable in these two examples, and 

 altogether conformable to the physiological views here taken 

 generally, is the curious correlation of all the tegumentary 

 parts with one another, their conduciveness to the same re- 

 sult, their great influence, and above all, the permanence of 

 their forms in the generic groups where they are observed. 

 The teeth are by no means so fixed a character. They vary 



