A MONOGRAPH OF THE BATS OF NORTH AMERICA. 87 



2. Vespertilio albescens CJeofl'. 



VesperilUo albescens GeoiT., Aunales du Mns., 1805, viii, 204; Temniinck, Monoi;. 

 Maiiimifcrt's, 1840, ii,244; Peters, MI?. Akiul. ]5crliii, 18(;6, 19; Dohson, Cat. Chi- 

 roi). Brit. Mus., 1878, 326; Alston, Biol. Ceutrali-Aiiier., Mam., 187!M882,24. 



Vespertilio hruaUiensis Spix, Siiniaruiu et Vespertilionum lirasiliensium species novae, 

 1823, 63, tab. xxxvi, tig. 8. 



Vespertilio leiivof/aster Wiod., Beitriig. Naturgesch. Brasil., 1825, ii, 271. 



Vespertilio nuJyilis Wagner, Schreb. Saiigeth., Suppl. 1844, i, 534. * 



Didfinosis. — A white ring of fur across the space between the angles 

 of the lower jaw conspicuous in alcoholic specimens. Auricle trans- 

 lucent, i^liciB usually present, but do not extend to the outer margin ; 

 thv dorsal aborescent lines infrequently present. Tlie tip of the tragus 

 is never acuminate; the convex basal half often ends abruptly and is 

 followed by a narrower terminal portion; the basal notch is defined by 

 the convex portion and the external basal lobe; the external basal lobe 

 is not antiflexed. The face is scarcely swollen. The forearm measures 

 from 31i'""' to 4(5""" long. The facial clump of glands is narrowed post- 

 eriorly; the supralabial groove does not extend to the mouth. 



V. albescens, h\ its larger phase, closely resembles V. (jry2fhi(s, from 

 which it can be distinguished by the shape of the tragus and the shape 

 of the clump of supralabial glands. When dwarfed, T^. albescens closely 

 resembles V. nitidiis, from which it may be distinguished by the 

 greater size of the thumb and foot. The membranes vary in color from 

 bluish translucent black to dense opaque black. The anterior surface 

 of the interfemoral membrane often whiter, that is to say, retains an 

 appearance as though it were washed over with a milky Huid. 



Vespertilio albescens, as seen by reference to the original description 

 (see Appendix), was so named from the white color of the tips of the 

 hair on the under surface of the body, a style of coloration in no wise ])e 

 culiar. The general appearance of the pelage must have been somber, 

 since the fur of the back is described as black, and that of the inferior 

 parts obscure brown. As in the case with other original descriptions, 

 it would be im])ossible, without examination of the type, to distinguish 

 this bat from others in the fauna, and we are compelled to rely upon 

 personal authority. Peters (M. B. Akad. Berlin, 1860, p. 19) rehabili- 

 tated V. albescens, but did not give a new diagnosis. He was (;ontent 

 to point out the fact that V. lencogaster, Wied,, and T^. nubilis, Wagner, 

 were the same as this species. Peters has been followed by Dobson, 

 Alston, and J. A. Allen. The author last named extended its range 

 from South America and Guatemala to Mexico. 



Vespertilio brasilicnsis, Spix, is described in terms similar to those of V. 

 albescens, with the marked exception tliat tlie fur of the under surface 

 of the 1)o<ly is black. But in a figure which acconqianies the descrip- 

 tion, tlie color is of the same shade as is commonly seen in V albescens. 

 So far as the figure is concerned, no one would hesitate h)ng in assign 



* Tlio last two names are here included on the authority of Peters, who has exam- 

 ined the types. 



