114 Merriam N'eio Species of T/iomomys. 



Measurements. Type specimen ( $ ad.): total length 2)57; tail verte 

 brae 71; hind foot 34. Average of 8 adults from type locality: total 

 length 228; tail vertebrae 69; hind foot 31.5. 



Thomomys clusius ocius sp. nov. 



Type from Fort Bridger, Wyoming. No. If^ff, $ ad., U. S. National 

 Museum, Biological Survey Collection. May 24, 1890. Vernon Bailey. 

 Original No. 1194. 



Characters. Similar to clusius but slightly smaller and much paler, the 

 upperparts pale buffy; sides of nose and region around mouth dusky 

 plumbeous; cheeks pale buffy gray; sides whitish, tinged with buffy; 

 feet and underparts white. 



Cranial characters. Skull like that of clusius but zygomata less spread 

 ing; temporal ridges a little more strongly developed; interparietal 

 larger: bullte decidedly larger. 



Measurements. Type specimen: total length 204: tail vertebra.- (50; hind 

 foot 2(1 Average of 8 adults from type locality; total length 197; tail 

 vertebnt 1 .77: hind foot 25. 



Thomomys idahoensis *p. nov. 



Type- from Birch Creek, Idaho. No. -jj -$$$$, $ ad., U. S. National 

 Museum, Biological Survey Collection. August 8, 1890. C. P. Streator. 

 Original No. 129. 



Characters. Size small; coloration pale. Similar in general to clusms 

 but much smaller and paler. 



Color. Upperparts grayish buff strongly washed with buffy fulvous, 

 often with 'pepper and salt' appearance: underparts, tail, and feet buffy 

 white. 



Cranial characters. Skull small and rather light, with enormous bulhe 

 and narrow zygomata. In general like clusius but much smaller: bulkc 

 much larger and more suollen; nasals long and rat her slender, with straight 

 sides. 



Measurements. Type specimen: total length 179; tail vertebrae 47; hind 

 foot 28. Average of 10 specimens from type locality: total length 172; 

 tail vertebra 51; hind foot 22.5. 



Thomomys desertorum sp. nov. 



Type from Mud Spring, Detrital Valley, Arizona. No. ;5-o-ii $ ad., 

 Merriam Collection. February 21, 1889. Vernon Bailey. Original No. 

 598. 



Characters. Size small; coloration buffy or golden fulvous, much as 

 in aureus. Does not require comparison with any known species. 



