234 ORYZOMYS. 



under surface; hind feet very long; soles naked, with six tubercles, 

 all very small except the posterior, which is very long and narrow; 

 upper margin of the orbit raised into a compressed crest, as in Sig- 

 modon." (Baird, 1. c.) 



KEY TO THE SPECIES. 



A. Fur coarse; tail longer than head and body; 

 hind feet very long. " Upper margin of 

 orbit raised into a compressed crest." 



a. Under parts white. PAGE 



a/ Above yellowish fulvous and black 0. nelsoni 235 



b/ Above ochraceous and black. 



a." Tail above dusky, whitish below O. albiventer 236 



b." Tail above brown, paler brown 



beneath O. crinitus aztecus 245 



c/ Above ochraceous fulvous 0. yucatanensis 236 



b. Under parts grayish white. 



a/ Above tawny ochraceous lined with 



black 0. panamensis 241 



b/ Above mottled blackish brown O. talamancce 241 



c/ Above rusty brown and black O. alfari 242 



c. Under parts whitish, or tinged with salmon 

 or buff. 



a/ Above pale grayish 0. peninsula 236 



b/ Above reddish brown and black O. couesi 236 



c/ Above mixed deep rufous and black 0. palatinus 237 



d/ Above dark rufous brown O. hylocetes 237 



e/ Above grizzled fulvous and black 0. rhabdops 237 



f/ Above dark fulvous and black, small 0. chapmani 238 



g.' Above dark fulvous and black, large. . . .0. c. caudatus 238 



h/ Above fulvous and black, paler 0. c. dilutior 238 



i/ Above blackish and fulvous O. c. saturatior 239 



j/ Above chestnut brown 0. bulleri 239 



k/ Above "deep dull fulvous" O. rufus 239 



I/ Above bright fulvous; beneath tinged 



with fawn O. fulgens 240 



m/ Above dark fulvous; under parts grayish 



white O. molestus 240 



n/ Above pale fulvous and black O. zygomaticus 241 



o/ Above grayish bistre O. cozumela 241 



d. Under parts buffy white. 



a.' Above fulvous brown lined with black. . .O. mexicanus 242 



