1915.] 



THOMOMYS FULVUS GEOUP. 



83 



Specimens examined. — Total number, 50, as follows: 

 Colorado: Antonito, 8; Conejos River (6 miles west of Antonito), 2; Gardiner, 2; 

 Salida, 9. 



New Mexico: Abiquiu, 1; Arroyo Hondo, 4; Chama River Canyon (above 

 Abiquiu), 1; Espanola, 8; Fort Burgwyn, 5; Qiiesta, 4; Pi,inconada, 2 ; Santa 

 Clara Canyon, 2; Santa Fe, 1 ; ^ Santa Fe (10 miles north), 1. 



THOMOMYS FULVUS DESERTORUM Merriam. 

 Desert Pocket Gopher. 



(PL VI, fig. 6.) 



Thomomys desertorum Merriam, Proc. Biol. Soc. Washington, XIV, 114, July 19, 1901. 



Type. — Collected at Mud Spring (10 miles southwest of Mineral 

 Park, southern end of Detrital Valley), Arizona, at about 3,400 feet 

 altitude in Lower Sonoran Zone, by Vernon Bailey, February 21, 

 1889. Type specimen in U. S. Nat. Mus., Merriam collection. 



Distribution. — Detrital and Big Sandy Valleys, northwestern 

 Arizona; east in the Grand Canyon to Prospect Valley (figs. 7 and 8). 



Characters. — Size small, hind foot 26 mm.; color bright ta^vny; 

 skull small, light, and smooth, with abruptly decurved incisors; sexes 

 very similar; mammae in 4 pairs. 



Color. — Summer pelage: Upperparts rich orange-ta^Tiy, or orange- 

 cinnamon, Hghter and brighter than mfulvus; ear patch, nose, and 

 cheeks dusky; underparts creamy white to light cinnamon; feet and 

 tail soiled whitish or buffy. Winter pelage: Duller and more yellow- 

 ish; upperparts bright cinnamon; underparts whitish to buffy ochra- 

 ceous. 



Slcull. — Small and Hght, smoothly rounded, not ridged or angular; 

 bullae small, but full and rounded, not flattened and angular as mful- 

 vus, nor large and prominent, as in aureus; basioccipital, as mfulvus, 

 wide with sharp keel. Dentition: Incisors bent dowTiward at right 

 angles to axis of skull. 



Measurements. — Type ad.): Total length, 200; tail vertebrae, 

 68; hind foot, 26. Average of 5 male topotypes: 195, 63, 26. Aver- 

 age of 4 female topotypes : 190, 60, 25.5 ShuU (of type) : Basal length, 

 33; nasals, 12; zygomatic breadth, 22; mastoid breadth, 17.5; alve- 

 olar length of upper molar series, 6.5. 



RemarJcs. — The color of this little gopher in summer pelage suggests 

 relationship to fulvus, but its cranial characters are so strongly 

 marked that it was originally described as a species. It may, how- 

 ever, probably be considered a depauperate Lower Sonoran desert 



1 In the mammal collection of the Academy of Natural Sciences of Philadelphia is a mounted skin Avith- 

 out skuU (No. 145) of a typical Thomomys pervagus. It is labeled "Columbia River,'' but the label has 

 been copied from the catalogue where origiaaUy no locality was indicated, and the locality of the pre- 

 ceding specimen has been given to it. This is evidently the specimen referred to (Proc. Acad. Nat. 

 Sci. Phila., VI, 1852, p. 5-3, PI. LXIV) as Geomys rufescens, donated by Col. Geo. A. McCaU. McCall's 

 specimens apparently were not labeled, but this collection of 70 mammals and bird skins was said to be 

 from California and Oregon. As pervagus is neither a California nor an Oregon form, the specimen in 

 question probably came from Santa Fe, N. Mex., where McCaU was previously stationed. 



