118 



NORTH AMEEICAN FAUNA. 



[no. 39. 



underparts paler, more ochraceous; feet and tail soiled whitish. 

 Young of the year, paler, more yellowish. A trace of long, rough fur 

 on the rumps of several breeding females is duller and darker, more 

 like the June pelage of douglasi. 



Sicull. — ^Relatively shorter and wider than in douglasi, with more- 

 spreading and more nearly parallel zygomatic arches, triangular inter- 

 parietal, larger buUse, V-shaped instead of U-shaped interpterygoid 

 fossa, and heavier molars; nasals narrow, with generally double 

 rounded posterior tips. 



Measurements. — Average of 5 topo types (c? ad.): Total length, 

 216; tail vertebrae, 67; hind foot, 29.5. Type (c? ad.): 220, 70, 30. 

 Average of 5 adult females: 210, 66, 28.2. Sicull (of type): Basal 

 length, 36; nasals, 14; zygomatic breadth, 23.7; interorbital breadth, 

 6.5; mastoid breadth, 19.4; alveolar length of upper molar series, 7.6. 



Remarks. — The relationship between douglasi and oregonus is 

 not very close and the question of continuity of range has not been 

 worked out. The Columbia River probably separates their ranges, 

 but they are near enough in characters to allow subspecific rank to 

 show their relationship. 



Specimens examined. — Twenty-eight, from type locality. 



THOMOMYS DOUGLASI YELMENSIS Merriam. 

 Yelm Pocket Gopher. 



(PI. VIII, fig. 11.) 



Thomomys douglasi yelmensis Merriam, Proc. Biol. Soc. Washington, XIII, 21, Jan. 

 31, 1899. 



Type. — Collected at Tenino, Yelm Prairie, Thurston County, 

 Washington, by Clark P. Streator, October 24, 1891. Type specimen 

 in U. S. Nat. Mus., Biological Survey collection. 



Distribution. — Prairies around south end of Puget Sound, Wash, 

 (fig. 5). 



Characters. — Very similar to douglasi, but with more-pointed ears, 

 duller and darker coloration, and conspicuous black ear patches; 

 zygomatic arches not widest at anterior angle. 



Color. — In faded October pelage: Upperparts dull hazel; nose and 

 sides of face dusky; ears and large ear patches blackish; underparts 

 buffy with irregular white patches; two specimens with white spots 

 on breast and one with white spots on side; feet and tail white or 

 soiled whitish. Winter pelage (just appearing on heads in October 

 specimens) dark umber on crown. 



Sicull. — Long and low like that of douglasi; slightly concave inter- 

 orbitally; zygomatic arches parallel or widest posteriorly; inter- 

 pterygoid fossa more nea.rly V-shaped; nasals narrower and more 

 deeply emarginate at posterior tips. 



