206 PROCEEDINGS OF THE ACADEMY OF [1897. 



form of Peromyscus canadensis has yet been secured. It is significant 

 that here also is to be found one of the largest tracts of old-growth 

 evergreen timber in the State. It is probable that systematic trap- 

 ping in the tamarack swamps of the more northern Counties of Bed- 

 ford and Susquehanna will show this and other " Canadian " species 

 to be abundant. South of this, however, along the entire eastern 

 extension of the Allegheny system east of the main ridge there 

 seems to be an absence of this species, but in Cambria County and in 

 Somerset County, near the Maryland line, there appears in the hem- 

 lock forests a form seeming to connect, in its diminished size and 

 darker colors, the Canadian Peromyscus with a similar species dis- 

 covered by the writer in the spruce forests which crown the lofty 

 summit of Roan Mountain, N. Carolina. The Red-hack Vole, Evoto- 

 mys, also reappears in Somerset County, the most careful trapping in 

 the intermediate region of Juniata and Huntingdon Counties failing 

 to reveal it. From these facts it would seem that the southern 

 extension of the typical Alleghenian mammals found in the northern 

 counties of the State is confined to a narrow strip of the main 

 western ridge through Clinton, Centre, Blair, Cambria and Somerset 

 Counties into West Virginia. In the latter State, owing to the 

 increasing elevation of the southern Alleghenies, these northern 

 types of mammalian life are enabled to bridge the warm Carolinian 

 zone as far south as northern Georgia, insensibly, but surely, appro- 

 priating those subtle modifications by which the climate of the 

 southern mountains has transformed Peromyscus canadensis into 

 Peromyscus nubiterrce, Evotomys gapperi into Evotomys carolinensis, 

 and Sciuropterus sabrinus into Sciuropterus silus. 



The author's collection of central Pennsylvania mam nials, forming 

 the basis of this paper, numbers about 600 specimens, the greater 

 part of which are skins and skulls, with careful measurements and 

 data taken in the field. Of these nearly 400 were taken by my 

 assistant, Mr. J. C. Ingersoll, during the fall of 1896, as already out- 

 lined, and represent an amount of laborious mountaineering and con- 

 scientious care, which not only do him the greatest credit but form 

 the only available means to a right understanding of the character 

 and distribution of the smaller mammals of the south-central portion 

 of the Commonwealth. The l*st enumerates 61 species and sub- 

 species. Of these 10 are listed as subspecies, 3 are exotic species, 2 

 (Black Rat and Lynx) are probably exterminated, and 3 (Bison, 

 Wapiti and Beaver) certainly exterminated. 



