72 Merriam — Tivo New Red Backed Mice. 



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

 side white ; fore and hind feet white. 



Cranial rharartcrs. — Skull large, rostrum long, especially as seen from be- 

 low ; braiucase large and strongly subqnadrate, flattened above ; zygomata 

 strongly spreading, the anterior root standing out rather abruptly from 

 rostrum ; audital ball;e large and strongly inflated ; incisive foramina 

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

 molar more irregular than usual. 



Re)narks. — Contrasted with Evotomys ohscurus from the west base of Mt. 

 Mazaina, E. mazama may be distinguished by its much jialer 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 ohscurus in 

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

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



Measurements. — Type specimen, (^ adult: total length, 160; tail verte- 

 braj, 54 ; hind foot, 19. Average of four adult c? 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). Tyjie No. 

 80413, (^ ^'^■1 ^^- ^- ^'^t. 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 gi'adu- 

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

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

 fore and hind feet soiled white; ankle and foreleg from elbow to wrist 

 dusky. 



Cranial c}Mractii's.—^^\\\\ short, particularly the rostrum; braiucase 

 subqnadrate and moderately flattened, but less flattened than in IC. ma- 

 zama; zygomata I)owed well outward, tiie anterior base standing square 

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

 loops crowded ; incisive foramina short. 



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

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

 E. maz(()na, but it is slightly smaller, the rostrum and incisive foramina 

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

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

 Externally the animal resembles Evotomys ovciderdalis from the Puget 

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

 de^itaUs, the latter being nairow and smootiily rounded like a small 

 Peromyscus. Probably E. oWur/ f.s is more nearly related to E. californicus 

 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. 



