60 



NORTH AMERICAN FAUNA. 



[No. 36. 



Color. — Upperparts dull ochraceous-buff (slightly paler than in 

 chryso2)sis) , sparingly mixed with black on the back, the median 

 dorsal band only faintly indicated; sides paler but without lateral 

 hne of buff; ears fuscous; underparts pinkish buff; fore feet buffy 

 white^ washed with brownish; hind feet hair-brown, becoming white 

 toward the toes; tail pale fuscous above, grayish white beneath. 



SlculL — Similar in shape to that of R. c. tolucx, but shghtly smaller, 

 with less inflated braincase; rostrum a little shorter and broader; 

 zygomata standing out a little more squarely anteriorly; nasals 

 long, ending on plane of premaxillse; interpterygoid fossa rather 

 wide (as in clirysopsis) ; bullae intermediate in size between those of 

 chrysojysis and tolucse; palatal foramina short and widely open; 

 enamel pattern of upper molars simple, with only a trace of a sub- 

 sidiary enamel loop. 



Measurements. — Average of 2 specimens from type locahty: Total 

 length, 165.5; tail vertebras, 90; hind foot, 20. Skull: (See table, 

 p. 81). 



Remarlcs. — This species resembles externally the members of the 

 chryso'psis group, but the absence of sudsidiary loops on the upper 

 molars makes it necessary to place it in the rufescens group in the 

 typical subgenus. It is apparently a connectant species between 

 the two subgenera. 



Speciinens examined. — Two, from type locality. 



REITHRODONTOMYS COLIM^ NERTERUS Merriam. 

 CoLiMA Harvest Mouse. 



Reithrodontomys colimm nerterus Merriam, Proc. Wash. Acad. Sci., Ill, 1901, p. 551. 



Type locality. — Sierra Nevada de Colima, Jalisco, Mexico (altitude, 

 6,500 feet). 



Distribution. — Known only from the type locality. 



Characters. — Similar to colimse, but ochraceous color more intense, 

 pelage shorter, and tail longer; skuU slightly smaller. 



Color. — Upperparts deep ochraceous-buff, nearly pure on sides, 

 mixed with black on median dorsal area; underparts heavily washed 

 with light ochraceous-buff; ears fuscous, shading to fuscous-black; 

 tail indistinctly bicolor, pale fuscous above, dusky drab below; feet 

 buffy white, shaded with dusky; ankles dark hair-brown. 



Slcull. — Shghtly smaller than that of colimse but of essentially similar 

 shape; nasals considerably shorter; interpterygoid fossa relatively 

 wide; enamel pattern of upper molars simple. Compared with 

 luteolus: Braincase narrower and higher; rostrum slenderer; nasals 

 broader at posterior end; bullae smaller but more inflated (rounder); 

 palatal foramina shorter. Compared with R, r. rufescens: Braincase 

 higher; rostrum and nasals shorter; bullae more inflated. 



