NATURAL SCIENCES OF PHILADELPHIA. 287 



III. 



In determining the species of Scotophilus of North America, I had been 

 influenced bv the authority of Major John Le Conte (Mon. on N. A. Bats) to 

 consider 5. carolinensis as distinct from S. fuscus, although suggesting at the 

 time that they might prove to be identical. I now venture to consider them 

 such, and make the former a synonym to the latter. This has not been done 

 hastily. It is not to be presumed that all the specimens of S. fuscus found in 

 this country are identical in every particular. They arrange themselves in 

 groups, of just sufficient definition to mislead the observer. But it is found, 

 upon careful comparison, that so vaguely are the boundaries of these groups 

 determined, that it is impossible to assign them precise limits. Among the 

 characters selected for this purpose, successively embraced and relinquished 

 (apart from the coloration of fur elsewhere noticed), are the infra-orbital fora- 

 men, whether it be well defined in front or open ; the zygomatic arch, whether 

 straight on inferior border and forming a right angle with the tuberosity of 

 superior maxilla, or curved on inferior border, and forming an obtuse angle ; 

 the inner side of orbital space, whether flat or convex ; the glenoid cavity, 

 whether transversely elliptical or lozenge-shaped ; the tragus, whether in- 

 curved at tip or straight ; the outer border of ear, whether emarginated or 

 nearly entire ; the nostrils, whether palmate or reniform ; and the proportion- 

 ate size of the foot and thumb. But it does not follow after all that I am 

 correct in this conclusion. A more acute observer than myself may yet divide 

 S. fuscus into sevt ral species.* 



The extent of the ex-liniital distribution of this species is not yet deter- 

 mined. M. Gervais thinks it probable and the extended study he has given 

 this group renders his opinion valuable that S. dutertfeus is identical with 

 "carolinensis," and that both S. innoxius and S. furinalis may be found in 

 North America. I have seen several specimens of S. fuscus from Mexico which 

 present no differences from those met with in the United States. 



Another specimen, however, from Mirador, Mexico, has peculiar coloration, 

 and may receive the following description : 



S. MIRADORENSIS, n. S. 



Head and auricle much as in S. fuscus. Inner border auricle inclined, ob- 

 liquely rounded; inner edge free ; anterior border nearly covering eye; tip 

 rounded, turned very slightly outward ; outer border scarcely if at all scooped 

 out ; basal third moderately re volute. External based lobe oblong and crescent! e, 

 not markedly turned inwards ; as long as interval between it and angle of mouth. 

 Tragus erect, nearly half as high as ear, straight on inner border, tip not in- 

 curved ; outer border divergent, slightly convex ; basal lobe obtusely rectan- 

 gular, turned somewhat forward. Nostrils snb-reniform ; posterior angle well 

 defined; space between nostrils as usual, naked, concave. Mental space illy 

 defined. The supra-orbital and gular warts as usual. Membranes light brown, 

 attached to base of toes ; phalangeal callosity of thumb marked ; tubercle 

 present on tibial side of foot ; a larger one on fibular side for membranous cal- 

 caneum. Joints of tail nine^; terminal and half penultimate free. Inter femoral 



* The following is a list of the smaller species of Scotophilus of Europe in the collection of the 

 Academy : 



Italy, Bon. Coll. Dr. T. B. Wilson. 



It is not improbable that specimen No. 510 is the type of .S'. Uwippe. This specimen appears to be 

 almost identical witli 509, S.pipistrellus. The prevailing: hueof all the above South Eur pean species, 

 excluding alcythce. is a rich chestnut-brown fur above, with the apical one-fifth of a gilc yellowish- 

 brown. Beneath fawu-browu at basal two-thirds; whitish at apical third. 



1S66.] 



