66 



ITORTH AMEEICAN FAUITA^ 



[No. 36. 



REITHRODONTOMYS HIRSUTUS Merriam. 

 Giant Harvest Mouse. 

 (PL III, fig. 1; PL VI, fig. 1.) 

 Reiihrodontomys hirsutus Merriam, Proc. Wash. Acad. Sci., Ill, 1901, p. 553. 



Type locality. — Ameca, Jalisco^ Mexico. 



Distribution. — Kjiown only from the type locality. 



Characters. — Size very large; colors much as in R. f. tenuis, paler 

 than in R. levipes. 



Color. — Upperparts ochraceous-buff, brightest on sides, sparingly 

 mixed on the back with blackish brown; underparts grayish wliite, 

 usually with a distinct tinge of light buff ; fore feet whitish, washed 

 with Hght buff; hind feet grayish white, tinged with dusky; ankles 

 fuscous; tail pale fuscous above, grayish white below; ears brownish 

 drab. 



Slcull. — Large and robust with a well-defined supra-orbital bead 

 which extends back to the parietals; braincase rather flat and some- 

 what narrowed posteriorly; zygomata contracted anteriorly; rostrum 

 and nasals short; ascending arms of premaxillse extending back of 

 end of nasals; audital bullae very small; palatal foramina short and 

 wide; upper molars with subsidiary enamel loops. 



Measurements. — Average of 5 adults from type locality: Total 

 length, 211 (203-233); tail vertebrae, 127 (122-143); hind foot, 21.8 

 (21-22), Skull: (See table, p. 81). 



Remarlcs. — This species is one of the largest in the genus, being 

 exceeded in size of skull only by R, tenuirostris, a widely different 

 species. So far as known, it has no near relative except levipes, and 

 from that it differs both in size and color. It agrees with it, how- 

 ever, in every important cranial character — ^heavy rostrimi, short 

 and wide palatal foramina, broad interpterygoid fossa, and small 

 bullae. 



In color, hirsutus bears a remarkable resemblance to R.f. tenuis, 

 which inhabits the same region, but is hardly more than haK the size 

 of the present species. 



Specimens examined. — Six, from type locahty. 



SEITHRODONTOMYS CHRYSOPSIS GKOUP. 



REITHRODONTOMYS CHRYSOPSIS CHRYSOPSIS Merriam. 

 Volcano Harvest Mouse. 

 (PL III, fig. 3; PL VI, fig. 3; PL VII, fig. 6.) 

 Reithrodontomys chrysopsis Merriam, Proc. BioL Soc. Wash., XIII, 1900, p. 152. 



Type locality. — Mount Popocatepetl, Mexico (altitude 11,500 feet). 



