Vol. V] TAYLOR— NEW SUBGENUS OF PHENACOMYS \^y 



Residents told us that green twigs on the ground beneath 

 the fir trees indicated not only the presence of a' Phenacomys 

 nest but also the fact that the nest was occupied. Although 

 this would not seem always to be so, since we found green 

 twigs under trees in which there were no nests, it would 

 appear to be iht rule. At any rate, green branchlets were 

 noted on the ground under most of the occupied nests w^e * 

 investigated ; and it was true in all instances where the nest 

 was occupied that fresh green fir branchlets were pulled into 

 the loose superstructure of dry twigs on top of the nest. 



Reference has already been made to the fact that the nests 

 found at Lierly's Ranch and Hearst, Mendocino County, were 

 made up of sticks too large to be transported by Phenacomys, 

 so doubtless originally constructed by the gray squirrel 

 (Scinrus griseus griscusj or the wood rat (Neotoma fuscipes 

 fuscipesj. The lone individual tree mouse taken at Lierly's 

 Ranch was found 50 feet up in a Douglas fir, in a nest 18 

 inches in diameter, built of sticks of fir and lined with "tree 

 moss" (really the net lichen, Ramalina reticulata) which 

 appeared to have been fluffed up by the occupants. 



Our studies of nests at Mendocino City showed that below 

 the level of the used portion of the nest there was usually 

 found a mass of decaying matter, sweating and steaming like 

 a pile of old manure or like green feed in a silo, a very large 

 part of the nest being made up of this material. In composi- 

 tion this mass was nothing more than the resin ducts of fir 

 leaves and net lichen with quantities of feces distributed 

 through it. Occasionally, but not often, this old slowly decay- 

 ing matter was relatively dry. 



Well defined galleries traversed the nests in various direc- 

 tions, providing ready communication between the inner nest 

 cavity and the outer world. When the nest was built all the 

 way around the trunk of the tree a circular gallery, running 

 around the trunk and communicating with runways leading 

 to the nest cavity and the exterior, was usually found. 



Bailey (1915, pp. 148-149) says some Phenacomys houses 

 had only one nest [inner nest cavity], and others had as many 

 as five. Concerning one nest examined by him he says : "The 

 twigs of which it was largely composed had settled in a half 

 decayed and earthy mass as solid as a muskrat's house, and 



