68 MONOGIJALMIS OF NOKTU AMERICAN EODENTIA. 



M. De Saussure has been more fortunate in handling Mexican TIesperomys 

 than he was in this case, for one of these specimens is an adult and the other 

 a young example of leucopus; neither of them shows the slightest departure 

 from the ordinary type. We have not met with either of these names in 

 print, and if, indeed, they were never published, we shall regret their appear- 

 ance on our page ; for a synonym once rooted is haul to eradicate. 



Now, passing over for a moment a certain Eastern United States variety 

 of leucopus that we shall be prepared to establish farther on, and likewise post- 

 poning consideration of the names "cognatus" and "umniculatus", as these 

 are best treated in connection with var. gossypinus, we will examine several 

 western names that we claim have no foundation. 



The first western "species" (so-called) that we shall notice, is Hesperomys 

 "texanus" of Woodhouse (type, No. 2559, Mus. Smiths., in alcohol, from 

 Western Texas). The author's description shows nothing whatever different 

 from ordinary leucopus, except small size (length, 2.10 ; tail the same) ; but 

 this, of course, is matched by any other ungrown leucopus. The character, 

 "legs white on their inner surface only" (i. e., color of back extending over 

 outside of legs), is not of the slightest consecjuence, since plenty of typical 

 leucopus show it, especially immature ones. In admitting the species, which 

 he places next to leucopus, Professor Baird found it "very difficult to charac- 

 terize it as distinct from leucopus, although it is very probable that the two are 

 distinct." He assigns "size and proportions about as in leucopus;" and his 

 table of measurements does not show any discrepancy. The ears are not 

 smaller, as given by both these authors. We fail to appreciate any distinction 

 in color, except a slight average paleness ; and for this we shall be abundantly 

 prepared after we have looked up var. sonoriensis. Finally, we tabulate the 

 several specimens that have been referred to texanus; it is the more surpris- 

 ing that Dr. Woodhouse should have described his specimen as distinct, since 

 he was well acquainted with leucopus, which, as he says, is "common in the 

 Indian Territory and Texas." 



