50 Zoology of Colorado 



Mexico, actually goes north unchanged to Monon, Baca County, 

 Colorado. West of its range, all the way from Coahuila to La 

 Junta, Colorado, is a race canescens of Allen, smaller, paler, with 

 longer and softer fur. N. dcsertorum of Merriam, a comparatively 

 small pale fulvous animal, extends from the northeast corner of 

 Lower California to a small area in Rio Blanco County, western 

 Colorado. It has also been taken by Warren at Mack, Mesa 

 County. All the above are Neotoma proper; the subgenus 

 Teonoma includes the mountain rats, or trade rats, the form so 

 abundant in our mountains being N, cinerca orolestes of Merriam. 

 Its interesting habits are fully described by Warren in his Mam- 

 mals of Colorado. N. c. arizonae of Merriam, found in Monte- 

 zuma and Montrose Counties, is smaller and paler, with less 

 bushy tail. N. c. cinnamomea of Allen, obtained by Warren in 

 northwestern Moffat County, is paler and redder than arizonae. 

 Our Sigmodontinae include Reithrodontomys, with grooved 

 incisors, and tail over half length of body, and the genera Ony- 

 chomys and Peromyscus, in which the incisors are smooth. Ony- 

 chomys has the tail less than half length of body, and soles hairy 

 on posterior half; in Peromyscus the tail is longer, often more 

 than half length of body, and the soles are naked. All these 

 animals have the size and appearance of mice, not rats, and will 

 not be confused with Neotoma. The species of Reithrodontomys 

 are called harvest mice; Warren notes that they are smaller than 

 the deer mice, with proportionately longer tails, which are slender, 

 scaly, and thinly haired, while the ears are prominent. R. 

 albescens of Cary is found from the sand hills of Nebraska to 

 Loveland, Colorado; R. montanus of Baird in the San Luis Valley; 

 R. megalotis aztecus of Allen in southwestern Colorado, north to 

 Grand Junction and Rifle; R. m. dychei of Allen in eastern Colo- 

 rado. Of Onychomys we have only the species 0. leucogaster of 

 Wied, but it is represented by two races, of which 0. I. arcticeps 

 of Rhoads belongs to the eastern part of the State, and 0. I. 

 melanophrys of Merriam to the west, extending into the Rio 

 Grande Valley in Costilla County. These are called grasshopper 

 mice. The deer mice or white-footed mice, genus Peromyscus, 

 are difficult to classify. There is one group with remarkably 

 large ears, including P. truei of Shufeldt and P. nasutus of Allen, 

 the latter originally described from Estes Park. Another group 



