MUEID^— ARVICOLIN.E— EVOTOMYS. 131 



Subfamily ARVICOLim 



The characters of the group having been given on page 2 in a manner 

 which suffices for present purposes, and some analysis of the genera being 

 represented in the table on pages 4-6, we may immediately proceed to con- 

 sider the various genera and species successively in detail. 



Genus EVOTOMYS, Coues. 



< Arrkola sp., Auctorum. 



< Myodes, Selys-Longchamps, Etudes de Miorom. 1839, 87. 



= Hypudmis, Keyserling & Hlasius, Wirbeltb. 1842 (type, Arricola glarcola), (not of Illiger, which in- 

 cludes Mus lemmus, amphibius, and arvalis). 

 — Hypudmis, Baird, M. N. A. 1857, 5Ki, 515, 518 (type, Arvicola gapperi). 

 = Evotomys, Coues, Proc. Acad. Nat. Sci. Phila. 1874, 186 (type, Mus rutilus, Pall.). 



The name "Hypudoeus" appears to have been loosely, if not indiscrim- 

 inately, used by authors; and,- before proceeding to its definition, we wish to 

 explain the above synonymy, in vindicating the necessity for a new generic 

 name. 



According to Agassiz, the name Arvicola, proposed by Lacepede in 1803, 

 applied to Mus amphibius and Mus arvalis, and therefore, of course, is out 

 of the question for the present genus. 



According to Baird, the name "Myodes", as used by Selys-Longchamps 

 (1839), is the same as Hypud&us, Illiger, and therefore conflicts with Myodes, 

 Pallas, of same date, applied to the Lemmings. 



"Hypudseus", Illiger, 1811, included Mus lemmus, a?nphibius, and arvalis, 

 and is therefore inapplicable to the present genus. 



But Keyserling and Blasius, in 1842, in separating the old genus Arvicola 

 into two sections, retained the name Arvicola for the largest and most compre- 

 hensive of these, and applied Illiger's term Hypudaius to the restricted group, 

 of which Mus rutilus, rubidus, glareola, gapperi, &c, are typical. Baird, in 

 1857, used Hypudaius precisely in the same sense that Keyserling and Blasius 

 had attached to it. 



It is simply the old question : Shall a synonym of one genus become the 

 tenable name of another genus ? Here, Hypudaius, Illiger, a synonym of 

 Arvicola, Lacepede, if not also a synonym of Myodes, Pallas, has been held by 

 Keyserling and Blasius and by Baird as the distinctive name of a different 

 genus. It is immaterial that these latter authors gave the term an entirely 



