MURID2E— SIGMODONTES— HESPEEOMYS AUIiEOLUS. 93 



4703, from the Southern States, probably Georgia, the under parts are not 

 white at all, nor even whitish, but cinnamon, only a little paler than the sides. 

 No. 981 has cpiite a black stripe along the back. No. 2964, from Illinois, is 

 interesting in several respects. In the first place, the feet are remarkably 

 small, less than in any Hesperomys we have seen, except michiganensis ; and 

 in some other respects, especially "buccis Jlavis", it corresponds better with 

 Audubon and Bachman's description of michiganends than the specimens we 

 have inferred to thai species do. The under parts, moreover, are white. The 

 general color of the upper parts, while showing unmistakable traces of the 

 peculiar orange shade of aureolus, are much watered with a darker hue. This 

 is another case of darker hue in Illinois rodents than elsewhere; for the 

 Arvicola riparius, Pitymys pinetorum, and Hesperomys leucopus, all show this 

 peculiarity. A Saint Louis, Mo, skin might be referable to this species with 

 a shade of doubt, were it not accompanied by a little suckling one, possibly 

 its offspring, which settles the case, and at the same time confirms the valid- 

 ity of the species in a very satisfactory way. This little creature is of the 

 same bright orange-cinnamon as the adults, while, as is well known, the young 

 of leucopus are, for some months, of a dark ashy-gray. 



I only venture to include in this series a specimen (No. 548) from the 

 Schuylkill River, Pa., with grave doubt. The animal appears to have been 

 skinned out of alcohul, and the yellowish tinge of the under parts may be 

 due to discoloration. In other respects, it is more like leucopus than aureolns, 

 having dusky ears, sharp line of demarkation along the sides, &c. 



Doubtless, after all, there are some who would prefer to consider H. 

 auroleus as a "permanent variety"»of leucopus, but they need to be reminded 

 that such course would remain simply a petitio principii until they explain 

 the difference between a "permanent variety" and a "species". 



The figure and description of Arvicola nuttalli, Harlan, agree very well 

 with the present species ; but, as they represent a bright-colored leucopus 

 quite as well, and contain nothing positively distinctive, I agree with Mr. 

 Allen that it is not necessary to supersede the well-known and very expressive 

 name aureolus. 



