106 University of California Publications in Zoology [Vou. 30

of the tail. There is a broad subterminal band of black, and the tip
is white, suffused with reddish. The inner webs, and part of the outer
webs, are white or gray, irregularly flecked with dusky. The outer
rectrix (present only on the left side) has the outer web barred with
blackish its entire length. Below, the tail is mostly white, with small,
irregular dusky markings. On certain of the upper tail coverts is the
only part of the body plumage of the bird where distinctly chestnut
markings appear.

Brooks’ specimen is peculiar in that but the three outer primaries
are emarginate, a condition that is not supposed to exist in the Buteo
borealis group of hawks, where the presence of four emarginate
primaries has been accepted as one of the diagnostic features of the
species. We examined the freshly killed bird carefully, and there is
no question but that the full number of primaries was present.

The adult female in the Provincial Museum, Victoria, differs some-
what from the two just described. It is a darker colored bird even,
with the concealed white markings greatly reduced in size and number.
The feathers on chin, throat, and upper breast are dusky to the base.
The plumage generally is not so worn as in our two birds, and there is
hardly a trace of white showing through on the breast.

The tail is quite different from those of the other two adults. There
is but a mere trace of rufous upon it. There is a terminal band of
black, 35 mm. to 45 mm. in width (widest on the outer feathers), and
above this the tail is crossed by a series of narrower bands, seven black
and eight light colored, the dark colored strips becoming broader
toward the base of the tail. The light colored areas are white on the
inner web, grayish on the outer. The tail differs from that of the
immature in the broad, black terminal band, in the lesser number of
narrower bands, in the more distinctly whitish color of the paler
areas, and in that it is more squarely truncate at the end. Individual
rectrices are broader and more square ended than those of the young
bird. The two central tail feathers of this adult are being renewed,
and are about one-third emerged from their sheaths. They are of
exactly the same character as the others, in interesting confirmation of
the fact that this type of plumage is retained year after year. The
older birds do not eventually acquire a red tail.

This specimen has lost one primary of the left wing, giving it an
appearance of having but three emarginate primaries on that side, a
condition which is probably responsible for the misidentification of
the bird as Buteo swainsoni at one time.