64 University of California Publications in Zoology | Vou. 17 
forms, contained in the Museum of Vertebrate Zoology, has revealed 
the existence of a definite intergradation between them through an 
extensive area in California. 
In males from points within the range of typical occidentalis, in 
the Sacramento Valley and in Humboldt, Marin, Napa and Alameda 
counties, about 72 per cent have the throat patches joined as in all 
male bi-seriatus. The other 28 per cent of the males is what we should 
have to rely on for the separation of these races if we held to this 
character alone. Our series of occidentalis from eastern Mendocino 
County averages about as large in size as a series of small bi-seriatus 
from Los Angeles County. It therefore becomes desirable to seek out 
some additional character as a criterion for the separation of these 
two forms, if they are, indeed, to be considered worthy of systematic 
notice at all. 
Nearly every male occidentalis I have examined can be distin- 
euished from bi-seriatus by the greater amount of light color on the 
underparts, particularly on the lower surface of the hind limbs and 
on the chest and between the belly patches. A single specimen of 
occidentalis from Monterey and ten or so of a large series from the 
coast of northern California have the parts mentioned dark greenish 
or slaty in color. A male from Bakersfield, and another from Little 
Rock Creek, Los Angeles County, each has an unspotted ght stripe 
down the center of the belly and cannot be distinguished from average 
occidentalis, although obtained well within the range of bi-seriatus. 
But these are exceptions in a very large series which shows the gen- 
eral duskier color of the subspecies bi-seriatus. 
The most interesting thing about this character of the color of the 
underparts is the distribution of the intergrades, which occupy a zone 
running from the coast near San Luis Obispo northeast to western 
Merced County, thence across the San Joaquin Valley to Coulterville, 
Mariposa County, then northward over the Sierras to eastern Modoe 
County. The range of occidentalis northwest of this zone contrasts 
in its greater humidity with the range of bi-seriatus to the southeast 
of it. 
In the intergrades the white chest, mid-ventral line and hind limbs 
are flecked by numerous dark scales, either widely separated (as in 
occidentalis), or jomed into a general dusky suffusion as in bi-seriatus. 
The body-length of individuals increases noticeably as one goes south 
through the Sacramento and San Joaquin valleys from Yolo and 
Solano counties into Fresno and Kern counties. This increase in size 
