216 ANATOMY OF THE WOOD RAT 



the intermediate position between Homodontomys and 

 Teonoma. In the other there has been modification chiefly 

 by the habitat and habits of the animal, following the more 

 scansorial propensities of Homodontomys, the more strictly 

 terrestrial ones of Neotoma, and the somewhat intermediate 

 preferences of Teonoma. This is comphcated, however, by 

 other tendencies, which might really be termed a third 

 trend, presenting heterogeneous evidence which it is difficult 

 properly to place. As an instance of this may be mentioned 

 the hghtness of some of the bones of Neotoma . with Homo- 

 dontomys being intermediate in this respect towards the 

 more robust condition of the bones of Teonoma. That this 

 is correlated in some way with habits seems likely, but our 

 knowledge of the subject is still too meager for further analy- 

 sis of the facts to constitute more than guess work. 



As previously mentioned, no attempt is made to settle 

 the purely taxonomic question of subgeneric validity, but it 

 might be mentioned that as the anatomical, , lifferences 

 between Teonoma and Neotoma are so much greater in 

 degree than between the latter and Homodonotomys, there 

 seem to be but two courses open, in the fight of our present 

 knowledge, to anyone who is interested in taking action in 

 the matter. If Teonoma is to be considered only a sub- 

 genus, then the name Homodonotomys should be suppressed ; 

 if the latter be retained as a subgenus, then Teonoma should 

 be elevated to the status of a full genus. 



