1918] Swarth: The Pacific Coast Jays of the Genus Aphelocoma 409 
have attained their full size, length of wing and tail are also equally 
characteristic in the young. In several instances in the present study, 
where localities have been represented by adults in worn, midsummer 
plumage, the appearance of young birds taken at the same time 
pointed unmistakably toward the relationships of the series in 
question. 
On the accompanying table the variable features in Aphelocoma 
californica are listed so as to show the differences occurring in the 
birds of the several faunal areas inhabited. Where there is little or 
no difference in a character in two or more of such areas, the dividing 
line is lightly indicated. Where there is an appreciable discrepancy 
this line is heavy. Thus in the diagram, differentiating characters 
are segregated by locality regardless of subspecifie names. 
It will be observed of the Cape San Lucas bird (hypoleuca) that 
in every particular it is sharply set off from its nearest neighbor, 
californica, so much so that, if, as seems highly probable, there is a 
stretch of country between the two uninhabited by the genus, cali- 
fornica and hypoleuca might well be considered distinct species rather 
than subspecies of the same form. It is true that although Aphelo- 
coma hypoleuca and A. californica as occurring in northern Lower 
California (A. c. californica) are so abruptly and absolutely different, 
hypoleuca and Sacramento valley californica (A. c. immanis) are dis- 
tinguished with difficulty ; but this seems to be a case of parallel modi- 
fication of widely separated forms, races that really have but little in 
common. 
It will also be noted upon the diagram, relating to the species as 
occurring in California and Oregon, that although no line of separa- 
tion can be drawn between any two adjacent regions for all the char- 
acters considered, certain divisions can be made by combination of 
various of the differentiating features. Disregarding the Cape San 
Lucas bird, it will be seen that beginning at northern Lower Cali- 
fornia there is increase of size northward; not evenly, however, for 
although a line drawn between the Santa Cruz and San Francisco 
Bay regions will separate smaller sized birds to the southward from 
larger ones to the northward of this point, there is no appreciable 
size difference between birds of the Santa Cruz area and northern 
Lower California on the one hand, nor between those of the San 
Francisco Bay area and Oregon, on the other. 
There is no appreciable difference in length of culmen from Cape 
San Lucas to Oregon (see table), but depth of bill increases north- 
