1908.] NATURAL SCIENCES OF PHILADELPHIA. 409 



specimens of Eptesicus fuscus from this region^^ have the color and size 

 typical of the species, the new form must be considered as a distinct 

 species and not merely a geographical race of fuscus. 



The probable origin of this species is a matter of some interest. 

 Occurring in the same territory and occupying the same habitat as 

 its near relative fuscus, neither the geographic isolation nor selection 

 theory seem to offer a satisfactory explanation. Neither the mutation 

 nor orthogenesis theory finds any difficulty in these facts. Moreover we 

 have here an apparent exception to Jordan's law of geminate species. 



Further information as to the distribution of this species is very 

 desirable.^^ 



In conclusion I wish to thank the authorities of the Field Museum, 

 the Academy of Natural Sciences of Philadelphia and the U. S. National 

 Museum for the identification of much of my material; and the latter 

 institution especially for its loan of valuable material. 



^^ Loveland, fide Miller, op. cit., p. 98. A single skin without skull in my own 

 collection from Boulder Canyon, approximate altitude 2,300 m., has the typical 

 brown color of E. fuscus. 



^' Miller, op. cit., p. 99, says of fuscus: "Verj^ pallid specimens are occasionally 

 taken in the Southwestern United States, but the number of skins available for 

 comparison is so small that it is impossible to determine the status of the form 

 wliich these aberrant individuals represent." It is possible that these specimens 

 are representatives of my new form, but not having seen them I cannot saj^ 



