1894.] NATURAL SCIENCES OF PHILADELPHIA. 217 



Externally, maglster is most conspicuously known from floridana 

 by its densely hairy and sharply bicolored tail. This member 

 is relatively shorter than in Jioridana, and the lateral divergence 

 of tlie longer hairs gives it a depressed appearance, which is almost 

 exactly repi-oduced in half-grown examples of the bushy tailed ash- 

 colored rat of the northern Rocky Mountains. The correlation of 

 development in this character and in the shorter ears, between ani- 

 mals of such widely separated but similar environments, both of 

 which trace their ancestry to progenitors inhabiting a serai- tropical 

 climate, is a significant fact. In body colors, magister is readily dis- 

 tinguished from florldana by its plumbeous grayness and lack of 

 brown above, by the fulvous areas of opposing sides of lower hind 

 neck reaching nearly across the throat, and by the blackish areas 

 around the eyes and at base of whiskers. 



It therefore appears that we have in N. magider a large cave rat, 

 quite distinct from the wood rat of the Gulf States, and which, so 

 far as existing remains are known to us at this date, is the same ani- 

 mal as N. pennsylvamca Stone. 



As it now stands, however, the case is a peculiar one. The evi- 

 dence in favor of making peiinsylvanica a synonym is conclusive so 

 far as it is based on known facts, but the impossibility of ascertaining 

 the perishable external characters of those individuals whose fossil- 

 ized remains formed the types of Prof, liaird's description, estab- 

 lishes a possibility that they represent an animal we would now 

 consider separable from the living form. Were the specific pecu- 

 liarities of the different members of the genus Neotoma based on 

 cranial characters of constant value, the identity of magister and 

 pennsylvaniea would be clearly estalilished l)y my examinations, 

 but as yet they have not been so distinguished by anatomists. 

 That it is probable good cranial characters can be formulated for 

 the species of this genus deserving recognition, I feel confident. On 

 this basis, as recently applied by Dr. Merriam,^ it is apparent to 

 me that ■pennsylvaniea will not stand as a specific name, nor can it, 

 from the very nature of the case, be a candidate for sub-specific 

 honors. 



The points confirmatory of the identity of fossilized and living 

 specimens of iV. magister, already demonstrated by cranial charac- 

 ters, may be stated: — 



■' Proc Biol. Sot-.. Wiisli., 1S94. i)]). 117-128. 



