420 University of California Publications in Zoology [ Vou. 17 
Aphelocoma hypoleuca Ridgway 
Type locality.—La Paz, Lower California. 
Range—‘ ‘Cape district of Lower California ..., north to about latitude 
28°’? (Ridgway, Birds of North and Middle America, 3, 1904, p. 331). 
Specimens examined from the following localities: 
Lower California—La Paz, 8; Miraflores, 10; El Sanz, 4; Sierra de Laguna, 
5; Santa Anita, 1; Cape San Lucas, 7; Triunfo, 1. 
Total 36. 
Distinguishing characters —The pale coloration of hypoleuca serves to dis- 
tinguish it from any of the related species or subspecies on the Pacifie Coast. 
The blue areas are distinctly lighter than in even the palest examples of 
immanis, and the under parts are of a more nearly immaculate white. 
No. 11917 (coll. of John E. Thayer), male, Sierra de Laguna, Lower Cali 
fornia, August 25, 1908. Blue areas, Neropalin blue; dorsum, light drab, suf- 
fused with bluish. 
Remarks.—It is a difficult matter to come to a decision as to the 
proper nomenclatural treatment that should be accorded this form, 
though it is my impression that it is best regarded as a distinet species, 
rather than as a subspecies of Aphelocoma californica. The one great 
objection to this course is the close resemblance of hypoleuca to the 
form of Aphelocoma occurring in northern California. Whether this 
possibly fortuitous general resemblance of the two is sufficient to out- 
weigh the several arguments in favor of their distinctness, is a ques- 
tion, but the fact remains that it is almost impossible to designate 
characters whereby hypolewca and series of immanis from certain 
points can be distinguished without fail. 
So much may be said in opposition to the concept of specific differ- 
ence. The arguments in favor of such a view are essentially as follows: 
1. The features in which hypoleuca differs from the form geo- 
graphically nearest to it (A. c. californica) are not in accord with 
the trend of variation observed in A. californica over its range as 
a whole. 
2. Between californica of northern Lower California, and hypo- 
leuca of the southern end of the peninsula, the change in appearance 
is abrupt, comparable to the difference between immanis.and wood- 
housei, where the latter meet in California. Two specimens of cali- 
fornica from Santana, Lower California (Thayer coll. nos. 6353, 6552) 
are indistinguishable from comparable examples from southern Cali- 
fornia. Santana is about midway the length of Lower California, 
and at a point where, if intergradation between californica and hypo- 
leuca occurs, specimens secured should illustrate this condition. That 
Bee 
