202 PROCEEDESrGS OF THE NATIONAL MUSEUM vol. no 



between Natal Brown and Benzo Brown distally ; bases slightly grayer, 

 hardly distinguished from tips. Hair of underparts Mouse Gray at 

 base, pale buff at tip; distinction between base and tip slight. 



Size averages medium for subgenus; forearm averages relatively 

 long. Rostrum relatively long and not depressed; anterior nares 

 (viewed from above) wide and rounded in posterior outline. First 

 upper incisor usually without trace of secondary cusp. 



Measurements: See tables 12, 18. 



Comparisons: Compared with P. t. ingens, P. t. virginianus is 

 more sooty dorsally and averages slightly smaller in all dimensions; 

 the first upper incisor rarely has a trace of a secondary cusp ; and the 

 rostrum is less heavy and inflated. 



Remarks: The Appalachian populations (P. t. virginianus) appear 

 to be isolated by no less than 600 miles from the nearest closely 

 related populations {P. t. ingens) in the Ozark Highlands. Despite 

 this separation, the two forms are not strikingly different, and although 

 there is no possibility of demonstrating intergradation between them, 

 they may be treated best as being conspecific. On the other hand, 

 the Appalachian populations of P. townsendii are specifically distinct 

 from P. rafinesquii, whose geographic range they overlap. This 

 peculiar pattern of distribution, perhaps related to Pleistocene dis- 

 turbances, is discussed in the section on history (p. 215). 



There is no obvious explanation for the limited and apparently 

 discontinuous distribution of the populations within the bounds of 

 the Appalachian Highlands. The species is relatively numerous, even 

 the most abundant bat in some caves, in two adjacent drainage sys- 

 tems in northeastern West Virginia. It has been found in at least 15 

 caves at the head of the Potomac River and in four caves at the head 

 of the Cheat River. All of these caves are in limestone, in an area 

 30 miles wide and 40 miles long. Three other populations have been 

 discovered away from this main body: One a few miles to the north 

 in Preston County, W. Va. (Kellogg, 1937, p. 450), another 150 miles 

 to the south-southwest in a limestone cavern in Tazewell County, Va. 

 (Howell, 1909, p. 68; Mohr, 1933, p. 49), and the third in a cave 200 

 miles to the west-southwest in Powell County, Ky. (Barbour, 1957, 

 p. 141), The intervening extensive limestone caverns, mostly well 

 explored, in Pocahontas, Greenbrier, and Monroe Counties, W. Va., 

 and in the Valley of Virginia do not seem to be occupied by the 

 species. 



Isolation such as apparently exists among the Kentucky, Virginia, 

 and West Virginia populations of this species favors dift'erentiation. 

 It is not surprising then that differentiation is evident, Virginia and 

 Kentucky specimens average smaller than those from West Virginia. 

 Kentucky and West Virginia specimens are similar in color to Virginia 



