New Mice from Mexico and Guatemala. 



125 



Characters. Size small ; ears large ; tail enormously elongated and 

 moderately haired ; fur long and soft ; color grayish -fulvous. 



Color. Upper parts gray anteriorly, becoming more and more suffused 

 with olivaceous-fulvous to the rump, which is pale fulvous; back slightly 

 darkened by black hairs, but no dark dorsal area; nose gray, with a 

 small whitish fleck on extreme tip ; ring round eye dusky ; under parts 

 huffy-whitish, becoming buffy on pectoral region and whitish on chin, 

 lips, and sides of nose; wrists dusky ; fore feet white; front of ankles 

 and upper two-thirds of metatarsus dusky ; rest of hind feet, toes, and 

 sides of ankles white ; tail dusky, indistinctly paler below. 



Cranial characters. Skull small ; rostrum short and narrow ; zygomata 

 squarely but narrowly spreading anteriorly, the outer sides strongly con 

 vergent anteriorly ; frontals narrow interorbitally without trace of supra- 

 orbital bead ; braincase broad and rather flat ; interparietal narrow ; 

 audital bullse small. 



Measurements. Type specimen : Total length 249 ; tail vertebrae 155 ; 

 hind foot 24. 



FIG. 20. Skull of Megadontomys thomasi (X 

 See page 115. 



