Mt-i'riinn — Xtir Specie's <>f llnniKtmys. 109 



Chdrdcivrx. — Size very small: back l)i'iyhl fulvous: undei'parts while. 

 Related io pcrditxx but color wholly dillVrent and cranial characters ilis- 

 t inct ive. 



Color. — Upperparts bright rusty fulvous, moderately mixed with dark 

 lipped hairs: nnderparts white: nose and region around mouth dusky. 



('r(tni(d r/uinirferx. — Skvdl very small: like that of prntiftii but ros- 

 trum and premaxillic decidedly narrower and smaller, and nasals falling 

 short of premaxilhe. 



Mr((.surt')iit'i>f,s. — Type specimen ( $ ad.): total length 208: tail verte- 

 hv;r ()S: hind foot 150. An adult female from type locality: total length 

 190; tail vertebrje (JO; hind IVk.i -il. 



Thomomys baileyi sp. nov. 



7\i/ji<' from Sierra Hlanca, Texas. No. v^yilj, 9 ad., U. S. National 

 Museum, iJiological Survey Collection. December 28, 1889. \'ernou 

 Bailey. ( )riginal Xo. 870. 



VlKtracterx. — Size small: coloration rather pale: upper incisors ])ro- 

 jecting strongly forward. 



C(/Z('/'. -Tjiperparts pale butfy I'uhous, \arying to ochraceous ami 

 strongl.x mixed with black-lipped hairs: underparts butly to salmon: 

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

 incisors projecting forward. 



('ra)iial characters. — 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- 

 maxilhe: bulhe medium. In general the skull re.sembles 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 i)Ost coronoid notch of mantlible. 



jr<'t(,fi/n')iiciitf<. — Type specimen ( 9 ad.): total length 220: tail verle- 

 bne 72: hind foot 152. Average of (i adults from type locality: total 

 length 212: 'ail vertebr;e (iS: hind foot :iO. 



Thomomys nelsoni sp. nov. 



Tt/pc from Parral. Chihuahua, Mexico. No. itti.t.ll, 9 ad., V. S. Na- 

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

 "W. Nelson and E. A. (Joldman. Original No. i:3,0:!.5. 



CJiin'acft'rx. — Size medium or rather small: related to bailey t but color 

 clicxtinit instead of yellowish fulvous, and with distinctive cranial char- 

 acters. 



dolor. — Upperparts pale dull chestnut brown mixed on midtlle of back 

 with black tipped hairs; underparts same color but much paler: nose 

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

 Irinrl lc(/ ronnny /cell elo/nt over anhie arid coccriiuj pari of foot. 



