236 M. I. G. Saint-Hilaire on an American Bat, 



As to the genus Atalaphus, formed of species without any incisors 

 it would be wholly anomalous, since it is a character of the Bat, 

 to have all the three kinds of teeth, and thus never to want the 

 incisors in both jaws at the same time; moreover the two species 

 referred by M. Raffinesque to the genus Atalaphus appear to be 

 Vespertiliones. In point of fact, the Vespertiliones sometimes 

 lose their incisor teeth, as M. Desmarest has observed, and two 

 individuals of that genus, so circumstanced, may, very probably, 

 have been mistaken for new species. The celebrated d'Azzara, 

 and other equally distinguished naturalists, have shewn us, by 

 their own examples, that the most skilful observer is not always 

 secure from similar errors. 



Thus, up to the present time, whenever the existence of Chei- 

 roptera of the same genus, common to both worlds, has been 

 announced, examination has always shewn that the report of this 

 simultaneous existence had no real foundation, and nature has 

 been fouud invariable in her rule of not producing Bats, formed 

 on the same type, in both the old and the new world. 



What Naturalist, seeing this unchanging constancy, will refuse 

 to admit as one of the characters of the family of the Bats, that 

 of being distributed over both worlds, but formed of genera al- 

 ways confined to one or the other exclusively ? Certainly no one 

 can be taxed with rashness for drawing so natural an inference, 

 an inference, however, which, justified by a multitude of pro- 

 babilities, had not been so by a single positive proof, and which, 

 consequently, a single discovery would be sufficient to overthrow. 

 Zoology is indebted to the celebrated traveller, M. Augustus 

 Saint-Hilaire, for the means of verifying this fact, not less impor- 

 tant for the consequences derived from it, than curious and re- 

 markable in itself. This is one of the fruits of that admirable 

 voyage already so important to the progress of Botany, and which 

 might have been equally, or even more so, to the advancement of 

 Zoology, if, as he has done with respect to his botanical labours, 

 M. A. Saint-Hilaire had been himself the historian of his zoo- 

 logical discoveries. This celebrated traveller, as all the world 

 knows, has lately explored Brazil, in which country he found 

 the Bat which is the subject of the present article : I shall give 



