1915.] 



THOMOMYS BOTT^ GROUP- 



49 



St. Helena, 3; Mount Sanhedrin (3 miles west of summit), 8; Mount Veeder, 2; 

 Novato, 6; Old Fort Crook, 20; Petaluma, 3; Picard, 9; Placerville, 2; Post 

 Creek, 2; Prattville, 1; Quincy, 6; Rumsey, 6; Slippery Ford, 4; Snow 

 Mountain (Colusa County), 3; Susanville, 3; Tower House, 5; Ukiah, 7; Vaca- 

 \ille (8 miles west), 7. 

 Oregon: Ashland, 2; Ferren, 3; Grants Pass, 27; Grizzly Peak (west slope), 5. 



THOMOMYS BOTT^ NAVUS Merriam. 

 Red Pocket Gopher. 



(PL IV, fig. 3.) 



Thomomys teucodon navus Merriam, Proc. Biol. Soc. Washington, XIV, 112, July 19, 

 1901. 



Type. — Collected at Red Bluff, California, by Clark P. Streator, 

 December 26, 1893. Type specimen in U. S. Nat. Mus., Biological 

 Survey collection. 



Distribution. — Sacramento Valley, Cal., from Battle Creek, Tehama 

 County, south to Tracy Lake, San Joaquin Valley (fig. 6) . 



Cliaracters. — Size much smaller than hottae; color lighter; skull 

 relatively shorter and wider, with more projecting incisors, interme- 

 diate to some extent between hottse and leucodon; mammse in 4 pairs. 



Color. — Winter pelage: Upperparts light rusty ochraceous, darker 

 on back, face, and nose; ears blackish; underparts pale buffy or 

 ochraceous; feet whitish. Summer pelage (as shown in one July 

 specimen from Marysville Buttes) : Slightly brighter and more fulvous 

 above and below than in winter. 



Slcull. — Short and wide with zygomatic arches widest posteriorly; 

 nasals short, cuneate, emarginate posteriorly; bullae not large but 

 smoothly rounded. From the skull of leucodon it differs in smaller 

 size, narrower interorbital constriction, orange coloration and rela- 

 tively heavier incisors. Dentition light; incisors slender, protruding, 

 and bright orange except the white tips. 



Measurements. — Average of 4 topotypes ( ad.): Total length, 

 203; tail vertebrse, 67; hiad foot, 27.5. Average of 4 topotypes 

 (9 ad.): 189, 61, 26.5. SJcull (of type, & ad.): Basal length, 35; 

 nasals, 13; zygomatic breadth posteriorly, 25; mastoid breadth, 20; 

 alveolar length of upper molar series, 7. 



Remarlcs. — By treating leucodon as a subspecies of hottse, it becomes 

 necessary to place navus under hottse, with which it connects at one 

 angle as it does with leucodon at another. While typical Sacramento 

 Valley specimens of navus are strongly marked, others would go 

 with one form as well as with another. Fairfield specimens may with 

 equal propriety be placed with hoUx, navus, or leucodon. Agaia, on 

 the east side of the Sacramento Valley, the gradation northward is 

 toward leucodon, and southward toward mewa. Wheatland and J ack- 

 son specimens, though having typical navus skulls, are dark and rich 

 in color, appro achiag leucodon. 

 98121^—15 4 



