Merrliiii) — J\" /'• Sprcles of Thotnomyft. 11 V 



Thomomys niger sp. nov. 



Type from Seaton, near mouth of Umpqua River, Oregon. No. 69,407, 

 $ ad., U. S. Xalioiial Museum, IJiological Survey Collerlion. October 

 6, 1894. J. E. McLpllau. Oriiiinal No. 1147. 



Characters. — Size medium: feet large: tail medium: cars sliort: liead 

 and body all round gr/o.s.y(y dale black with greenish iridescence: nose duller, 

 feet and tail white, sometimes irregularly blotched with dusky. 



Cranial cliaraders. — Slcull of medium size, massive, showing well de- 

 veloped temporal ridges: inlcrparietal oval or broadly subtriangular; zy- 

 gomata moderately spreading and rounded; nasals emarginate, strongly 

 aud abruptly narrowed on posterior two-thirds. 



Remarks. — In coloration the 0. specimens at hand from the lyjie locality 

 strikingly resemble T. orizabnc from .southern Mexico. They differ from 

 orizuhir in having less black on the feet and tail, and in marked cranial 

 characters. The nearest relative of T. niger appears to be T. donglasl 

 from the Columbia River. It differs from dougUm, apart from color, in 

 slightly smaller size and in the following cranial characters: frontals 

 narrower interorbitally: zygomata rounded instead of angular, their 

 outer sides parallel instead of diverging anteriorly; nasals abruptly con- 

 stricted between anterior and middle thirds and narrower posteriorly 

 (instead of having straight sides); bulhe heavier anteriorly; molar serie.s 

 of same length as in douglasi but broader; incisors strikingly large and 

 broad: underjaw deep, the angular process much more heavily devel- 

 oped. 



Measurements. — Type specimen { $ ad.): total length 22."); tail vertebra^ 

 SI: hind foot 150. Average of 5 adults from type locality: total lenjjth 

 •215; tail vertebne 72; hind foot :10. 



