INTERRELATIONSHIPS OF GENERA 



57 



Asia, where no species of Microtus occurs, members of the 

 Pitymys group have been able to persist on the surface of the 

 ground, leading the lives of normal Microtines, and they have 

 undergone a process of cranial specialization exactly parallel 

 with that which, in other places, has been undergone by the 

 species of Microtus. These peculiar Asiatic representatives of 

 the genus Pitymys constitute the genus Neodon. 



Hg.lb. 



Fig. 5b 



Fig. 296.— Cheek-teeth of Neodon. 

 b. Left lower molars (same specimens as in Fig. 29a). 



In Neodon the fur is soft and full, but is not highly modified 

 as is usual in Pitymys; the moderately large ears, provided 

 with a distinct antitragus, are evident above the fur ; the tail is 

 moderately long and is fairly well clothed ; the fore and hind 

 claws are about equal ; usually the sole has six pads, although 

 these are sometimes reduced to five. The mammary formula is 

 the primitive one, 2 — 2=8. 



The skull is nearly as in Microtus. The temporal ridges 

 fuse in adults to form a weak but linear median interorbital 

 crest; the squamosals, frontals, and parietals are correspond- 

 ingly modified with age. The palate is normal. The auditory 



