72 Merriam Two New Red Backed Mice. 



tail bicolor, with sharp line of demarkation ; upper side dusky, under 

 side white ; fore and hind feet white. 



Cranial characters. Skull large, rostrum long, especially as seen from be 

 low ; braincase large and strongly subquadrate, flattened above ; zygomata 

 strongly spreading, the anterior root standing out rather abruptly from 

 rostrum ; audital bullya large and strongly inflated ; incisive foramina 

 very long; enamel loops of molar teeth not crowded ; those of last upper 

 molar more irregular than usual. 



Remarks. Contrasted with Evotomys obscurus from the west base of Mt. 

 Mazama, E. mazama may be distinguished by its much paler coloration, 

 longer tail, and by the dimness or absence of the dusky patch on the 

 foreleg just above the ankle. The skull differs from that of obscurus in 

 the much greater length of the rostrum and incisive foramina. The 

 crowns of the molar teeth are longer, and the loops less crowded. 



Measurements. Type specimen, cT adult: total length, 160; tail verte- 

 bne, 54 ; hind foot, 19. Average of four adult ^ from type locality : 

 total length, 157; tail vertebrae, 52; hind foot, 18.75. 



Evotomys obscurus sp. nov. 



Type from Prospect, Upper Rogue River Valley, Oregon (at west base 

 of Mount Mazama, altitude about 2600 feet or 800 meters). Type No. 

 80413, $ ad., IT. S. Nat. Mus., Biological Survey collection. Collected 

 August 29, 1896, by Edward A. Preble. Original No. 1455. 



General characters. Size rather large, tail medium ; coloration dark ; 

 dorsal area dull and ill defined. 



Color. Sides of head and body and head from nose to forehead dark 

 gray or grayish bister ; dorsal area very dull umber brown, passing gradu 

 ally into color of sides ; under parts buffy white, the plumbeous basal fur 

 showing through; tail sharply bicolor, dusky above, whitish beneath; 

 fore and hind feet soiled w r hite; ankle and foreleg from elbow to wrist 

 dusky. 



Cranial characters. Skull short, particularly the rostrum; braincase 

 subquadrate and moderately flattened, but less flattened than in E. ma 

 zama; zygomata bowed well outward, the anterior base standing square 

 out from rostrum; audital bulUe large; crowns of molar teeth short, the 

 loops crowded ; incisive foramina short. 



Remarks. Evotomys obscurus is very much darker than E. mazama, and 

 has a decidedly shorter tail. In general form the skull resembles that of 

 E. mazama, but it is slightly smaller, the rostrum and incisive foramina 

 are decidedly shorter, and the braincase is less flattened. The crowns of 

 the molar teeth are shorter, and the enamel loops much more crowded. 

 Externally the animal resembles Erotomy* occUlriitulis from the Puget 

 Sound country. The skull, however, differs strikingly from that of occi 

 dentals, the latter being narrow and smoothly rounded like a small 

 Peromyscus. Probably E. obscurus is more nearly related to E. californicm 

 of the northwest coast region of California than to any other species. 



Measurements. Type specimen: total length, 155; tail vertebrae, 47; 

 hind foot, 17. Average of three specimens from type locality: total 

 length, 148; tail vertebrae, 46; hind foot, 17. 



