Merriam Xwr Xjtecivs of Tfwmomyn. 109 



C/(r<ietcrx. Sixe very small; back bright fulvous; underparts white. 

 Related to perditux but color wholly different and cranial characters dis 

 tinctive. 



Color. Upperparts bright rusty fulvous, moderately mixed with dark 

 tipped hairs: underparts white; nose and region around mouth dusky. 



Cranial character*. Skull very small; like that of perditux but ros 

 trum and premaxilhe decidedly narrower and smaller, and nasals falling 

 short of premaxilhe. 



^f<'((xur('lllents. Type specimen ( $ ad.): total length 208; tail verte 

 bra 08: hind foot 30. An adult female from type locality: total length 

 190; tail vertebrae 00; hind foot 27. 



Thomomys baileyi sp. nov. 



Type from Sierra Blanca, Texas. No. ^Hlo 9 ac ^-> U. S. National 

 Museum, Biological Survey Collection. December 28, 1881). Yernon 

 Bailey. Original No. 870. 



dmracterx. Sixe small; coloration rather pale; upper incisors pro 

 jecting strongly forward. 



Color. Upperparts pale buft'y fulvous, varying to ochraceous and 

 strongly mixed with black-tipped hairs; underparts buffy to salmon; 

 region around mouth dusky: inside of cheek pouches and feet whitish; 

 incisors projecting forward. 



Cranial character*. Skull small; zygomata widely spreading, some 

 times broadest posteriorly; temporal ridges marked; interparietal sub- 

 quadrate: nasals emarginate behind and ending nearly on plane of pre- 

 maxilla 1 : bulla* medium. In general the skull resembles that of toltecus, 

 but it may be distinguished not only by the protruding upper incisors, 

 but also by the longer nasals which are notched instead of truncate be 

 hind, longer rostrum, broader interorbital region, less bulging occiput, 

 and much wider and more open post coronoid notch of mandible. 



J/^/.v/m/^/cAv. Type specimen ( 9 ad.): total length 220: tail verte 

 bra 1 72: hind foot 32. Average of adults from type locality: total 

 length 212: tail vertebra' (>S: hind foot 30. 



Thomomys nelson! sp. nov. 



Type from Parral, Chihuahua, Mexico. No. J)6, lol, 9 ad., U. S. Na 

 tional Museum, Biological Survey Collection. September 18, 1898. E. 

 W. Nelson and E. A. Goldman. Original No. l^OJW. 



Character*. Sixe medium or rather small; related to baileyi but color 

 chestnut instead of yellowish fulvous, and with distinctive cranial char 

 acters. 



Color. Upperparts pale dull chestnut brown mixed on middle of back 

 Avith black tipped hairs: undernarts same color but much paler; nose 

 and region around mouth abruptly dusky; feet whitish, but broirn of 

 hind ley coininf/ icell <l(c/< <'</ an hie anil coceriny part of foot. 



