_T. t. fossor_, 4; Cascade Creek, La Plata Co., Colo. Av. 215 57 29 32.6 14.2 22.0 19.0 6.0 7.5 0.7 16.2 7.3 Min. 204 51 28 31.3 13.6 21.5 18.0 5.7 7.1 0.5 15.9 7.0 Max. 223 63 30 34.0 14.8 22.9 19.6 6.3 7.8 1.0 16.3 7.5 No. 13684 (C. M.) _T. t. ravus_, 1; topotype 241 71 28 35.7 14.5 24.4 21.5 6.2 7.8 2.7 17.1 8.1 No. 178868 (U. S. N. M.) _T. t. pygmaeus_, 1; Fossil, Wyo. 167 52 20 24.0 10.2 16.5 14.8 5.2 5.6 0.7 11.1 5.8 _T. t. ocius_, 3; topotypes Av. 201 60 25 30.0 13.5 20.5 17.9 6.2 7.2 0.8 15.0 7.4 Min 196 57 25 29.9 13.0 19.9 17.5 6.1 7.1 0.5 14.7 7.3 Max. 205 64 25 30.1 14.0 21.5 18.6 6.3 7.3 1.0 15.3 7.5 _T. t. parowanensis_, 4; Britts Meadow, Beaver Mountains Av. 221 58 29 33.2 14.5 22.8 19.0 6.0 7.8 0.9 15.4 7.3 Min. 207 50 28 30.5 12.8 22.7 18.6 5.8 7.4 0.5 14.7 7.0 Max. 240 66 30 34.8 15.5 23.0 19.6 6.2 8.1 1.5 17.8 7.7 _T. t. levis_, 2; topotypes Av. 203 65 27 28.1 11.1 19.2 17.7 6.1 6.9 0.8 13.0 6.8 Min. 199 61 26 28.0 10.6 18.9 17.5 5.8 6.6 0.6 12.8 6.6 Max. 206 70 27 28.2 11.6 19.5 17.9 6.4 7.2 1.0 13.2 7.0 ---------------------------------------------------------------------- =Thomomys bottae= (Eydoux and Gervais) _Thomomys bottae_ is a southern species that, within the Great Basin, reaches the most northern limits of its distribution in Utah. The animals of this species inhabit the lower valleys, and with the exception of the Oquirrh Mountains, inhabit also the mountains in that part of the state west of the central mountain ranges. The specific characters are: Sphenorbital fissure present; incisive foramina posterior to infraorbital canal; anterior prism of P4 rounded; interparietal relatively small; lambdoidal suture straight in region of interparietal, in Utah specimens. =Thomomys bottae aureiventris= Hall _Thomomys perpallidus aureiventris_ Hall, Univ. California Publ. Zooel., 32:444, July 8, 1930; Univ. California Publ. Zooel., 37:3, April 10, 1931. _Thomomys bottae aureiventris_ Goldman, Proc. Biol. Soc. Washington, 48:156, October 31, 1935. _Type._--Male, adult, skin and skull, No. 43980, Museum of Vertebrate Zooelogy, University of California; Fehlman Ranch, 3 mi. N Kelton, 4,225 ft., Box Elder County, Utah; September 27, 1929; collected by Louise Kellogg; original number 451. _Range._--Northwestern Utah, and extreme western Utah as far south as the southern end of the Deep Creek Mountains.