324 University of California Publications in Zoology [Vol.12 



Museum and of the United States Biological Survey, 62 specimens, as 

 follows, all from Marin County: Vicinity of Point Reyes, 3 to 5 

 miles west of Inverness, 12 ; Inverness, 5 ; Olema, 15 ; Lagunitas, 2 ; 

 "Nicasio" (probably in near vicinity of San Geronimo), 26; Mil- 

 liard, 2. 



Relationships and Ecology. — Eutamias sonomae shows itself to be- 

 long primarily to the Upper Sonoran and lower Transition zones, 

 chiefly in the chaparral association, though locally invading the mar- 

 gins of the forest. The species further belongs to what has been called 

 the Clear Lake subfauna, namely, the aggregation of animal species 

 occupying the semi-humid inner coast ranges and intervening valleys, 

 lying between the narrow coastal Redwood fauna on the west and the 

 Sacramento fauna on the east, and extending from the vicinity of San 

 Pablo and Suisun bays north into western Trinity County. Eutamias 

 hindsi has similar zonal and associational restriction, but belongs to a 

 more humid area, namely, that occupied by the Marin subfauna. This 

 is a section of the coast belt proper, lying entirely within Marin County, 

 and extending from Point Reyes eastwardly to include the slopes and 

 foothills of Mount Tamalpais. Eutamias townsendi ochrogenys be- 

 longs to the Transition and Boreal zones in their narrow, humid-coast, 

 faunal divisions. It is a dweller in chaparral and forest, and has not 

 been found south of Freestone, Sonoma County. At the latter point 

 sonomat and ochrogenys have been taken in the same lines of traps, as 

 also at a point about seven miles west of Cazadero, Sonoma County. 

 The ranges of these two chipmunks thus not only meet, but actually 

 overlap to a slight extent. On the other hand, the range of hindsi is 

 separated from the ranges of both ochrogenys and sonomae by a belt 

 of country apparently unfit associationally for the existence of any 

 one of this group of chipmunks. Hindsi is thus quite isolated from 

 any of its relatives (see fig. 1). 



It may be remarked that hindsi appears to be much nearer in aggre- 

 gate of characters to ochrogenys than is sonomae. The latter is thus 

 an extreme departure from the townsendi stock. Sonomae reminds 

 one in several respects of Eutamias quadrimaculatus of the western 

 flank of the central Sierra Nevada, and the species just named may 

 well be a still further manifestation in the townsendi series. 



Eutamias merriami pricei, of the Santa Cruz subfaunal area, be- 

 longs also to the townsendi group. It resembles sonomae in general 

 aspect, but differs constantly and markedly in smaller ear, in dull 

 gray instead of white postauricular spot, in light gray instead of 



