ORDER CARNASSIER. 115 



the upper, are infinitely closer than in the roussettes. It is 

 manifest, therefore, that the smaller number of teeth in the 

 eephalotes is the result of natural condition, and not the 

 effect of age. 



The characters which we use in the classification of ani- 

 mals do not all possess an equal value, or rather the same 

 characters do not possess the same value in the different 

 subdivisions of the animal world. They acquire importance 

 when they are observed to be permanent in certain natural 

 groups of living beings ; but on the other hand, they lose 

 it, and can only be employed in a secondary manner, when 

 in other genera they are found to vary from one species to 

 another. 



The application of these principles to the consideration 

 of the skin of the bats, undoubtedly bestows a certain pre- 

 eminence on the characters derived from the various modi- 

 fications of the cutaneous system. This, however, constitutes 

 little more than the knowledge attainable by the com- 

 monest observers. A bat is recognised by the dimensions 

 of its arms, the membrane of which proceeding from the 

 sides forms one of the principal attributes of the ani- 

 mal. No attention is paid in this case to the conformation 

 of the other parts, to the state of the viscera, to the number 

 and structure of the teeth, and finally to the habits of the 

 being. The consideration of all these appeared superfluous, 

 after the predominant character of the family had been 

 ascertained. 



The bats, however, were found to differ very materially 

 from each other. As an example of this difference, we 

 may mention two genera, in one of which the development 

 of the cutaneous system is the least considerable, and the 

 greatest in the other. The first are the frugivorous bats, 

 which we have just noticed under the names of roussettes and 

 eephalotes ; the second are those sanguinary cheiroptera. 



