Vol. V] TAYLOR— XEIV SUBGENUS OF PHENACOMYS 157 



on the fleshy portions of the fir needles and the cortical portions 

 of young fir shoots, leaving the resin ducts and stripped shoots 

 to be incorporated into the nest structure. 



11. It seems probable that each individual tree mouse 

 ranges freely through the foliage of several trees in the vicin- 

 ity of its home nest-tree. 



12. Probably Phenacomys does not hibernate, though it 

 may become less active or altogether inactive during the cold- 

 est weather. 



13. The nests vary much in size and in altitude above the 

 ground. A majority are built against or near the trunks of 

 the trees. In some localities old gray squirrel nests have been 

 occupied by the tree mice. All nests examined at Mendocino 

 City were apparently of original Phenacomys construction. 

 Twigs, branchlets, resin ducts of fir leaves, and net lichen 

 (Ramalina reticulata) were the chief materials used. The 

 inner nest cavity was of soft material, either the resin ducts of 

 fir leaves or tree moss. The nests increase in size with age; 

 whether the increment is due to gradual accumulation of 

 material or to annual additions at some particular season is 

 unknown. Some of the nests seem to have been deserted. 



14. Young have been found in the nest in February and 

 in July. Numbers of young actually taken were three per 

 family in four instances, two per family in four additional 

 instances, and one in a single case. 



15. The number of females in our collections is dispropor- 

 tionally large. It is possible that females are actually more 

 numerous than males, and also that our methods of capture, 

 involving the destruction of nests, have resulted in a larger 

 number of females being taken. 



16. Apparently only one family occupies a nest. 



17. There is evidence which seems to show that males live 

 in nests separate from those of the females for at least a part 

 of the year, the male nests being smaller and different in other 

 respects from the family nests ; but the data are as yet incom- 

 plete and inconclusive. 



18. Probably Phenacomys longicaudtis and P. alhipes are 

 derived from the same species, doubtless a member, past or 

 present, of the subgenus Phenacomys. Several interesting 

 questions regarding the characters of longicaiidns and alhipes 

 and their relation to habits and environment await answer. 



