﻿July, 1896.] 



LIST OF GENERA AND SUBGENERA. 



9 



Althoug'li the voles aud lemmings may usually be distinguished at a 

 glance, there are certain genera and subgenera the exact position of 

 which is not at first apparent. Thus the species of Lagurus. although 

 voles, so closely resemble lemmings in external appearance that their 

 true relationships have been only very recently detected. On the 

 other hand, Synaptomys, a true lemming, has much the superficial 

 appearance of certain forms of JHcroius. 



LIST OF GENERA AND SUBGENERA OF ^IICROTIN^. 



Genera. 

 Synaptomys. 



Lemmus. 

 Licrostonyx. 

 Plienacomys. 

 Evotomys. 

 Microti! s. 



Sutfjenera. 

 Mictomvs. 



Eothenomys. 



Anteliomys. 



Lagurus. 



Alticola. 



Hyperacrius. 



Phaiouiys. 



Pedomys. 



Pitymys. 



Chilotus. 



Microtus. 



Arvicola. 



Neofiber. 



Fiber. 



Types. 

 Synaptomys coojoeri. 

 Synaptomys innuitus. 

 Lemmus lemmus. 

 Dicrostouyx torquatus. 

 Phenacomys iutermedius. 

 Evotomys rutilus. 

 Microtus arvalis. 

 Microtus melauogaster. 

 Microtus cliinensis. 

 Microtus lag-urus. 

 Microtus stoliczkanus. 

 Microtus fertilis. 

 Microtus blythii. 

 Microtus austerus. 

 Microtus pinetorum. 

 Microtus oregoni. 

 Microtus arvalis. 

 Microtus terrestris. 

 Microtus alleni. 

 Fiber zibethicus. 



The following groups are known to occur in both hemispheres: 



Lemmus. Microtus (geuus and subgenus). 



Dicrostonyx. Lagurus. 



Phenacomys? Pitymys. 



Evotomys. Arvicola. 



The following groups have been found in the Old World onlj^: 



Eotlienomys. Alticola. 

 Anteliomys. Hyperacrius. 

 Phaiomys. 



The following groups have been found in America only: 



Synaptomys. Chilotus. 

 Mictomys. Neofiber. 

 Pedomys. Fiber. 



GEOGRAPHIC DISTRIBUTION. 



The subfamily 21icroihue is distributed throughout the extratropical 

 region of the Xorthern Hemisphere. In the north some members of 

 the group approach the extreme limit of mammalian life, while in the 

 south a few species enter the northernmost edge of the tropics. The 

 subfamily, which is clearly boreal in origin, reaches its highest develop- 



