Merriam American Wood Rats. 119 



The upper molar series is of more nearly equal breadth through 

 out, the anterior molar not being so broad relatively as in the 

 other groups. The postpahiUl notch is usually narrow, though 

 it is broadened anteriorly in N. fuscipes macrotis of southern Cali 

 fornia. The frontals increase in width but slightly from before 

 backward, never expanding abruptly behind the interorbital con 

 striction as in the leucodon series. The anterior lobe of m - is 

 completely divided by a deep sulcus on the inner side into two 

 loops, except in fuscipes, in which the sulcus is relatively shal 

 lower and more anterior in position, the division being less com 

 plete than in other species. So far a known the group is re 

 stricted to the Upper Sonoran and Transition Zones, where it 

 ranges from southern Mexico (States of Jalisco, Michoacan, 

 Mexico, Puebla, and Vera Cruz) northward in the interior to 

 Colorado and northern Arizona, and along the Pacific Coast to 

 Oregon. 



(3) Neotoma desertorum group. Neotoma desertorum and inter 

 media* constitute the third group into which it is convenient to 

 divide the restricted genus. The group is not very sharply de 

 fined, some forms of intermedia coming very close to aberrant 

 forms of the leucodon series. The frontals increase in breadth 

 gradually from before backwards, much as in the pinetorum, group 

 not suddenly behind the constriction as in the leucodon. series. 

 There is no supraorbital bead in typical desertorum, but intermedia 

 shows a decided tendency to the formation of such a bead. The 

 postpalatal notch is narrower than in any other division of the 

 genus. In dental characters the group resembles the leucodon 

 series, the molars being decidedly broader anteriorly than poster 

 iorly, and m L being made up of three transverse loops, the an 

 terior of which is but faintly indented by the antero-internal 

 sulcus. The members of the group inhabit the Sonoran deserts 

 of northern Mexico and the southern United States, ranging from 

 Chihuahua and Sonora northward to northern Utah, northern 

 Nevada, and middle California. 



* Neotoma intermedia Rhoads inhabits the valleys of the coast reigon of California, 

 south of Monterey Bay. A somewhat paler form, usually more or less suffused with 

 pale ochraceus buffy, inhabits San Gorgonio Pass and the western edge of the Colorado 

 Desert. It was provisionally named gilva by Rhoads, and has just been renamed venusta 

 by True (in a publication received since the present paper went to press), but seems 

 hardly entitled to the distinction of a separate name. N. californica Price seems to be a 

 typical intermedia. Two subspecies, albigula Hartley from south and west Arizona, and 

 melanurq nob, from Sonora, are here recognized. 



