474 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



tliicker. The mandible is not so stout as it is in N. leucodon, and lias 

 a less pronounced angular process; but the most characteristic differ- 

 ence in the mandibles of the two species consists in the longer and 

 more highly arched coronoid process of N. leucodon, the two species 

 being comparable, in this regard, in extreme cases to the genera 

 Onychomys and Peromyscus. The teeth are shown in fig. 118. 



Fig. 117.— Neotoma cumulator. Skull of type, a, dorsal view; b, ventral view; 



r, lateral view. 



Habits and local distribution. — Tliis large wood-rat is found in abun- 

 dance on both shores of the Colorado River from the Gila to the Gulf of 

 California, and extends its range westward down the Salton and New 

 rivers to points north of the Boundary Line in California. Its houses 

 are usually built under the drooping branches of the large mesquites of 

 this region, which commonly trail upon the 

 ground, the lowest branches often being incor- 

 porated with the nest materials and affording 

 convenient and well-worn avenues to the tree- 

 tops. Most of these large, straggling trees show 

 where wood-rats have gnawed away large sec- 

 tions of bark from the branches, leaving the 

 white underlying wood exposed. The tallest 

 branches are reached and denuded, producing 

 an effect that can be seen from a great distance, 

 as bands of wliite along the treetops. This rat 

 also feeds upon the seeds of a gourd known by 

 the name of "Coyote melon." The large round fruit of this gourd was 

 usually seen among the heterogeneous materials piled up to form its 

 enormous nests. More than fifty coyote melons were counted in one 

 such heap, together with enough other materials to have filled a large 

 wagon bed. From Yuma to Cooks Wells these dwellings were con- 

 spicuous under nearly every mesquite tree. We drove several rats 

 out by setting fire to their mounds of debris. It is in this way that the 



Fig. lis.— Neotoma cumu- 

 lator. Crowns of molae 



TEETH of type, a, LOWER 

 SERIE.S; 6, UPPER SERIES. 



