A MONOGRAPH OF THE BATS OF NORTH AMERICA. 97 



naraed, but the tluuiil) is larjicr and the external basal lobe a mere no- 

 dule. 



V. agilis and V. roUois which appear to be sufficiently distinct to war- 

 rant placing them in varieties of V. nigricans.* V. yumanensis of the 

 Monograph of 1864 is undoubtedly an immature specimen of the same 

 species. All the varieties of V. nigricam exhibit a disposition for the 

 upper portion of the tragus to be crenulated; this is marked in 1'. yu- 

 manensis. In typical expressions V. nigricans from Brazil as well as 

 the varieties from Peru (also described in the doubtful T". oxyofus, Pe- 

 ters) exhibit creuulations; the character, however, can not be relied 

 upon as distinctive, since individuals of V. gryphus from eastern locali- 

 ties of the United States occasionally exhibit it. 



SJiiill and teeth as in V. gryphus, excepting that the crenulated cin- 

 gulum of the maxillary lateral incisor is less well developed. 



Characters of immature specimens. — The colors of immature speci- 

 mens, excepting the aberrant V. yuiuauensis, are more black on the 

 dorsum than in the adult. The tips are obscurely and irregularly 

 tipped with brown on the dorsum about in the same manner as the 

 tips are silvery in L. noetivagans. On the venter the distribution of 

 the gray tips is more uniform. The white color of the under parts of 

 the jaw (seen also in T". albescens) is absent in the immature. In an 

 individual 28'" long no fur was seen on the upper parts of the head 

 and trunk except over the neck where a patch of olive brown hair was 

 seen. The sides of the neck were also sparsely covered with hair of the 

 same color. The under parts were thinly covered with very short 

 whitish hair. Tlie upper third of the interfemoral membrane and all 

 the thighs were rather thickly covered with coarse olive-brown hair. 

 The tips of the fourth and fifth fingers were marked by a few minute 



*Tho varieties of T. nigricans embrace all forms which I describe, I la the proceed- 

 ings of the Academy of Natural Science, of Philadeljihia, in 1886 (Notes on the Ves- 

 pertilionidai of Tropical America), containing the names of V. viundus, V. cincinnus, 

 V. exiguus, V. obscurus, V. exilis and T^ tenuidornalis. I now look npou these provi- 

 sionally described forms either as geographical or pedomorphic. The first four men- 

 tioned, namely, V. mitndus, V. exiguus and V. obscurus belong to the dark variety, 

 while V. cincinnus resembles V. nigricans from the chestnut-red tints on the dorsal 

 fur. V. exilis and V. teniiidorsalis again are of the V. nitidus type in the color of the 

 dorsal fur. A due consideration of my statements in this paper would have clearly 

 shown that these forms were never distinctly offered as species, but tliat they were 

 submitted provisionally only under their separate names. It was hoped that the 

 the descriptions might bo appended without confusion to the available meager diag- 

 noses of the South American species. My position in this nuitter has been misunder- 

 stood. If I had denoted these varieties by number, or any other arbitrary means, it 

 would have been to my mind as significant as naming them. According to the method 

 of the Nuttal Ornithological Club of naming geopraphical sub-species by trinomials 

 some of these names may get be available in studies of T". nigricans and T^. nitidus. 



The likelihood that tropical species of Vesperiilio extend their range along the en- 

 tin; western coast makes it desirable to have exact knowledge of the South Ameri- 

 can forms. With the exception of 1^ albescens (which is undoubtedly distinct from 

 V. nigricans) I have no acquaintance with these species. T^ pohjthrix and V. oxyotua 

 are probably synonyms of T". nigricans. 



U\—^o, 43 7 



