240 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



Like that oi oilier genera known in early zoological times, the synonymy 

 of Myodes is involved. First ranged under Mus, then sharing the term 

 Arvicola with the rest of its subfamily, it has also had three names more par- 

 ticularly applied to itself— Hypudasus (Illiger, 1811); Myodes (Pallas, 1831); 

 and Lemmus (Linck, 18 — ). Hypudceus, as originally framed, included Mus 

 lemmus, amphibia*, and arvalis, and, according to some authorities, ought to 

 be restricted to the first species mentioned {lemmus); but, according to 

 others, it is applicable to either one of the three species Illiger put in it. But 

 it has of late been so carefully characterized by Keyserling and Blasius, in its 

 application to Mus rulilus, &c, that if it is to be retained at all (which we do 

 not think should be done), doubtless it is best assigned to rutilus. The 

 choice, then, narrows to Myodes and Lemmus; we have not the authorities 

 at hand to decide the case, but the balance of opinion is in favor of Myodes. 

 Both these genera, as originally based, had a much wider application than is 

 now admitted. In strict technical interpretation, both Myodes and Lemmus 

 are synonyms of Arvicola Lacepede, 1803. Georychus Rich. And. is, of 

 course, out of the question ; Illiger' s Georychus having been based upon an 

 animal of an entirely different family. 



Recent investigations, particularly the admirable memoir of Middendorff, 

 have resulted in reducing the number of nominal species of Myodes (as above 

 restricted) to three — M. lemmus, M. obensis, and M. schisticolor . There is no 

 question of the identity of "helvolus" and "trimucronatus" of Richardson, 

 Audubon, and Bachman ; and nothing appears opposing Middendorff's view 

 that the North American animal (including, besides the two supposed species 

 just named, M. albigularis of Wagner) is the same as M. obensis of the Old 

 World. Rather, the question is whether a still further reduction will not be 

 required. It would need but a little change in coloration to transform obensis 

 into lemmus itself; while, regarding schisti-color , it is a suspicious circum- 

 stance that here we have a nearly gray or slaty lemming, just as, in the case 

 of Cuniculus torquatus, we have a gray one in what is called C. lagurus. 

 The inference in this case is self-suggestive. But this is a question we do 

 not propose to enter upon here; our business being simply the determination 

 of the North American species. 



