108 Merriam New Microtus from Mexico and Guatemala. 



those of the last upper molar (which agrees with Microtus proper) and in 

 the general appearance of the molar crowns, which resemble Microtus 

 instead of Phenacomys. 



Microtus guatemalensis sp. nov. 



Type from Todos Santos, Huehuetenango, Guatemala (alt. 10000ft.). 

 No. 76777, $ ad., U. S. Nat. Mus., Biological Survey Coll. Collected Dec. 

 30, 1895, by E. W. Nelson and E. A. Goldman. Orig. No. 8960. 



Characters. Size medium ; coloration very dark ; end of nose blackish ; 

 lips white ; tail short and rather scantily haired ; fur very long and soft, 

 nearly hiding the ears. 



Color. Under parts everywhere slate black; extreme tips of hairs on 

 upper parts mixed dark golden fulvous and black, the resulting color diffi 

 cult to describe but near the ' mummy brown ' of Kidgway's ' Nomen 

 clature of Colors ' ; end of nose surrounding nose pad blackish ; edges of 

 lips white; tail concolor, blackish. 



Cranial and dental characters. General appearance of skull as in Microtus 

 pennsylvanicus or mexicanus but less constricted interorbitally ; audital 

 bulke very large and swollen ; jugal rather broadly expanded vertically ; 

 incisive foramina very rectangular of nearly equal breadth throughout 

 and truncate at both ends; anterior root of zygoma rather strongly notched 

 in front and standing out squarely so that the jugals are nearly parallel. 

 Dentition peculiar: incisors broad and long; molars broad and heavy : 

 m^ with 2 completely closed triangles on outer and 1 on inner side, with 

 open posterior loop elongated and curved to form 2 salient angles on inner 

 side. 



Measurements. Type specimen : Total length 155 ; tail vertebrae 40 ; hind 

 foot 21 . Average of 20 specimens from type locality : Total length 150 ; 

 tail vertebrae 37 ; hind foot 21. 



