Antiquity of the Cheiroptera. S3 



and consequently, that they have a certain more or less striking 

 disproportion among their members, and especially that of the 

 anterior ones, compared with the trunk ; and, secondly, that 

 they are more or less carnivorous, and consequently have the 

 dental apparatus more or less fitted for this purpose, or in other 

 words, have the molar teeth closer together, more numerous, and 

 beset with sharper tubercles. The regular arrangement of the 

 bats in a series, then, must be founded, first on the degree of 

 the development of the cutaneous expansions which enable them 

 to fly, and of the parts which sustain them, as the anterior ex« 

 tremities in general, and their digits in particular, also the tail| 

 which, by being prolonged more or less backwards, and beyond 

 the feet, enlarges so far the interjemoral membrane, because, in 

 fact, it unites the posterior members. Thus, in this point of 

 view the first species considered will be those which, in propor- 

 tion to the size of the body, have the smallest flying apparatus, 

 and also the smallest tail ; and the last species will be those in 

 which the flying apparatus attains its greatest development, af- 

 fecting in the same way the bony machinery connected with it. 

 The second portion of the organization of the Cheiroptera, 

 which will assist in determining their natural methodical ar- 

 rangement, is the state of the dental system, as it is found 

 more and more carnivorous and insectivorous. Now, this cha- 

 racter is determined, in general, by the presence of a greater 

 number of teeth, and especially by the more acute arrange- 

 ment of the tubercles upon their crowns. Hence a degree 

 of importance which progressively increases from the incisors, 

 — which exhibit many variations, not only in their number but 

 in their form also, according to age and species, and to such an 

 extent that they may quite disappear, — to the canines, — .which 

 are never wanting, but are more or less developed, — and espe- 

 cially to the molars, which must be studied in the most mi- 

 nute manner as to their number, their relative proportions, and 

 also the number and proportions of their tubercles. After the 

 minute study which I have directed to this portion of the dental 

 system of the bats, I may mention I have only hitherto found 

 five combinations, to which we may attach the names which 

 M. F. Cuvier has attached to several. 



