A MONOGRAPH OF THE 15ATS OF NORTH AMERICA. 71 



Both the internal and extei-nal basal lobes are near together and form 

 the lower end of an ellipse of whicli the tip constitutes the ujjper end. 

 In contrast with Ktrivoiila and Xataliis the s(;allops come well forward 

 in front of the conch. Both sides of the auricle in good specimens are 

 usually marked with raised arborescent lines. In further contrast with 

 Kerivoula and Natalus (genera which have the same number of teetli 

 aS Vespertilio) a phalanx is present in the second manal digit. The 

 third digit is scarcely longer than the combined lengths of the body 

 and the lower extremity, while an oblique tibial line is present on the 

 wing membrane. The scallops of the auricle are membranous {i. c, 

 not thickened), and are not incurved toward the tragus in the manner 

 Avhich is so conspicuously the case in Adelonycterh (q. v.). The proto- 

 cone of the third upper premolar is well defined. The post-digital nerve 

 of the fourth interspace arises from the side of the fourth metacarpal 

 bone near the middle.* 



The exact relations which obtain between Adelonycteris, Vesperugo 

 and the older genus Vespertilio, have not been determined. This arises 

 from the tact that minute variations in the numbers of teeth in bats 

 appear to be less denotive of structural peculiarities elsewhere in the 

 economy that is the case with the mammalia generally. Dobson (/. c.) 

 places Adelonycteris, Vesperugo and Lasionycteris in the same group, 

 each being the type of a sub-genus. But the intervals between mem- 

 bers of the group are most unequal. Adelonycteris and Vesperugo can 

 scarcely be separated except by the teeth while Lasionycteris has dis- 

 tinguishing characters in many parts of the periphery. 



While the species of Ves2)ertilio are exceedingly variable, it is of in- 

 terest to note that the wings are quite constant in form. Scarcely any 

 distinctions are discernible between these i)arts in species so remote in 

 areas of distribution as those of Europe and America. The shape of 

 the tragus is of more exact specific value than the wings and on the 

 whole yields the best single character of the skin surface. The inter- 

 femoral membrane is variable and is of much less value than the 

 tragus in denoting the constancy of species. The same may be said of 

 the auricle, for its shape and proportions are more generic than specific 

 in significance, though it must be conceded that the size of the first 

 scallop and the character of the outer border above the scallop dis- 

 tinguish varieties. At best the American species are less sharply dis- 

 tinguished from one another than are those of the old world. In 

 sui)port of this statement the ensuing notes are presented of my ob- 

 servations on a few well-known exotic forms: 



r. muricola (India).— Nostril with coriui -well defiued with pioniiuent margins, 

 border of nostril at muzzle imperfectly limited, septum recedeut obscure. Muzzle 



*ri'8pcrliUo, according to Cones and Yarrow (Wlieehr Exjiedition, 1875). includes 

 1990 

 all bats with 2233 Pr^'molars. These (-haracters define respectively the genera 



(as defined by them) Vesperus, VcHpernyo, VeKperidcn, iind VcHpertilio. 



