106 



NOETH AMERICAN FAUNA. 



[no. 39. 



Slcull. — Long and narrow, with uniformly arched outHne; temporal 

 ridges prominent and parallel in old age; nasals long and narrow, 

 and pointed at posterior tip, with a slight expansion back of middle; 

 interparietal triangular; auditory meatus slender; bullae medium, not 

 so full and rounded as in huUatus. Dentition medium; incisors bent 

 at right angles to axis of skull. 



Measurements. — Type (9 ad.): Total length, 220; tail vertebrae, 

 57; hind foot, 30. Topotype ( not fully ad.): 205, 50, 30. Slull 

 (of type): Basal length, 38; nasals, 15; zygomatic breadth, 23.5; 

 mastoid breadth, 19.7; interorbital breadth, 6.5; alveolar length of 

 upper molar series, 8. 



Remarks. — This is a well-marked local form of the talpoides group 

 occupying the great arid San Luis Valley, in open sage brush of the 

 Transition Zone. At present it may be isolated from other forms of 

 the group except fossor, by which it is surrounded in the timbered 

 mountains and from which it may have been derived. More prob- 

 ably, however, it is a more recent derivative of clusius which has 

 entered the valley through one of the passes. 



Specimens examined. — Total number, 18, as follows: 



Colorado: Blanco, 1; Creston, 1; Fort Garland, 2; Medano Ranch, 5; Saguache 

 (12 miles northwest), 1; San Acacia, 8. 



THOMOMYS COLUMBIANUS Bailey. 

 Columbia Pocket Gopher. 



(PI. VII, fig. 12.) 



Thomomys fuscus columbianus Bailey, Proc. Biol. Soc. Washington, XXVII, 117, 

 July 10, 1914. 



T^/^g.— Collected at Touchet, Walla Walla County, Washington, by 

 Clark P. Streator, September 10, 1890. Type specimen in U. S. 

 Nat. Mus., Biological Survey collection. 



Distribution. — Plains of southeastern Washington and northern 

 Oregon (fig. 5). 



Characters. — Size slightly smaller than talpoides, slightly larger than 

 quadratus, colors paler than either, about as in JisJieri; skull heavier 

 than in quadratus; claws moderately stout; mammae in 6 pairs, 

 inguinal 2-2, abdominal 2-2, pectoral 2-2. 



Color. — Summer pelage: Upperparts light wood brown or buffy 

 gray; sides and belly pale buffy gray; ear and postauricular patch 

 black; nose slaty; tail gray with white tip; feet whitish. Winter 

 pelage slightly grayer. Young very gray. 



Slcull. — Smaller than that of talpoides, with shorter, wider nasals; 

 larger and longer than that of quadratus, rather heavy and angular; 

 lateral ridges well developed in adults, approximately parallel; bullse 



