MAMMALS OK THE MKXICAN BOUNDARY. 



489 



of convex surface. Young, mouse-gray above, white below, with feel 



and tail dusky. 



Cranial and dental characters. The skull of this species is readily 

 distinguishable from that of Neotoma intermedia of the same region by 

 its larger size, peculiar shape, and much wider interpterygoid fossa. 

 The anterior loop of the first upper molar is not divided by a sulcus as 

 it is in N. mexicana. 



Remarks. — I have examined specimens that were intermediate in 

 characters, both external and cranial, between Neotoma fuscipes 

 /microtis and A', intermedia. They were found in leaf-nests in oak 

 trees, and I am disposed to consider them as hybrids between the two 

 species. Neotoma fuscipes macrotis is an arboreal species, building its 

 nests in hollow trees or among their branches, while X. intermedia 

 resides in the open country, usually making its home among the 

 cactuses. 



Habits and local distribution. — The San Diego wood-rat builds its 

 nest in tall evergreen oaks. The nest, which is composed largely of 

 twigs and leaves of the oak, resembles that of the eastern gray squirrel. 

 I once set fire to a nest and saw, besides the wood rats, two large tree 

 lizards (Sceloporus) come out of it. This species does not always 

 remain near trees. On July 3, 1894, I saw one in a clump of cactuses 

 on Cottonwood Creek, Lower California, and shot it from my horse. 

 The spot was a dry, open waste, perhaps 5,000 yards from the stream. 

 Several of our specimens were obtained by shooting into nests. 



Mi 1 1. sun merits of 12 specimens collected of tin <ji mis Neotoma fuscipes macrotis. 



a American Museum of Natural History. 



iholic. 



