120 Merriam American Wood Rats. 



(4) Neotomci nrlznutc group. Neotoma arizonss and N. lrj>i<l<i* 

 Thomas stand somewhat apart from the other subdivisions of 

 Neotoma proper, having bushy tails like those of Tcummm, only 

 smaller. In cranial characters they are hardly separable from 

 the desertorum group. They inhabit a small area on the southern 

 part of the Colorado Plateau in northern Arizona, northwestern 

 New Mexico, and southeastern Utah, and seem to be restricted 

 to the lower part of the Upper Sonoran Zone. 



Respecting the descriptions of new species which comprise the 

 bulk of the present paper, it should be remembered that each re 

 lates to a particular pelage. As a rule the summer and winter 

 pelages are different, the winter coat being grayer, the summer 

 coat more ochraceous or fulvous. In some species the summer 

 coat becomes more fulvous or even rusty with age, and the tips 

 of the black hairs wear off, changing the appearance of the ani 

 mal materially. 



Neotoma leucodon sp. nov. 



Type from SAN Luis POTOSI, MEXICO. No. 50,137 ^ ad. U. S. Nat. 

 Museum, Department of Agriculture Collection. Collected August 14, 1892, 

 by E. W. Nelson (Original number 3076). 



Measurements (taken in flesh). Type: Total length 358; tail vertebrae 

 164 ; hind foot 38.5. Ear from anterior base 30 (in dry skin). 



Average measurements of 7 males from type locality : Total length 352 ; 

 tail vertebne 160 ; hind foot 39. Average of 3 females from 'type locality : 

 Total length 342; tail vertebne 156 ; hind foot 37. 



General characters. A large species related to Neotoma micro- 

 pus but differing materially in color and in cranial and dental 

 characters. 



Color. Upper parts ochraceous-buff tinged with fulvous and plentifully 

 lined with black hairs ; sides relatively free from black hairs ; nose and face 

 between eyes grayish ; underparts white, with plumbeous underfur on sides 

 of belly ; fore and hind feet pure white ; tail sharply bicolor, blackish above, 

 white beneath. 



Cranial characters. Skull with the broad frontal platform of micropus and 

 floridana, but with sides of frontals decidedly upturned and postpalatal notch 

 narrow ; ascending branches of premaxilke very long, nearly reaching plane 

 of narrowest part of interorbital constriction ; nasals narrow behind and rel 

 atively short, barely cutting plane of orbits; jugals short as in Justices; 

 length of palate from incisive foramina to postpalatal notch nearly or quite 

 equal to length of incisive foramina : audital bullre large ; infraorbital va- 



*The status of N. lepida is not very clear. If the type is not a small female of N. 

 anzonce, it must be very closely related. 



