A New Species of the Genus Nyctinomus. 239 



the membrane of the wing, is of the same colour as that which 

 covers the abdomen ; a very few hairs are observable at the upper 

 portion of the tail, included in the interfemoral membrane, and 

 on the surrounding part of that membrane. 



I have thought it right to make only one species of all these 

 varieties ; in fact, I find in the same, or in several individuals, 

 the different intermediate shades, between yellow-brown and 

 black-brown ; so that I observe the yellow-brown Bat pass suc- 

 cessively to a deeper tint, then to a still deeper, and ere long to 

 black-brown. These different Bats which I refer to the same 

 species, are moreover perfectly similar in point of size and form. 

 It is well known besides, how much the colour of the Bat's skin 

 is liable to vary according to its age, sex, the time of year, &c. 



Omitting their generic characters, the ears are further remark- 

 able for the folds or transverse wrinkles, which are found, per- 

 haps less strongly marked, in the Nyctinomus of Bengal, but do 

 not exist at all in that from Egypt. The ears of the first two, are 

 somewhat less ample ; the tail, of a moderate size, (its length I 

 have given already) is surrounded at its upper half, and a little 

 further, by the interfemoral membranes, a very narrow prolonga- 

 tion of which, accompanies it to about a third or fourth part of the 

 lower half. I have not found any muscular band (brides) in this 

 membrane, which is rather larger than that of the Bengal Nyc- 

 tinomus. The membranes of the wings are shaped as in the 

 Asiatic Bat, and most of the Molosses, and have not the singular 

 form which prevails in those of the Nyctinomus of Egypt ; they 

 are rather wider in the Brazilian Nyctinomus than in its con- 

 geners, but they are shorter ; the humerus is slender and short ; 

 the phalanges pretty long. 



Such are the principal characters, which connect the new Bra- 

 zilian Bat with the other Nyctinomi ; and those which dis- 

 guish it from them. I think that I have sufficiently established, 

 on the one hand, that the bat of M. A. Saint-Hilaire is a true Nyc- 

 tinomus ; on the other that it is a new species of that genus, which 

 has hitherto been formed of bats of the old world exclusively. 

 I have but one observation more to make. I have been careful, 

 in the description, to point out how much the Nyctinomi of 



