vot. 1v.] Birds of San Pedro Martzr. 229 
Several days were spent at various camps between this point 
(7000 feet) and the gulf slope which was not reached until May 
23. ‘The return march was taken up May 27 and San Diego 
reached June 7. 
During our southward march the migration was at its height 
and at the time that we left the higher parts of the mountain new 
arrivals were seen almost daily; it is not improbable that among 
these late arrivals some Sonoran species might have been found 
had our time permitted a more thorough investigation. It is 
probable, however, that most of the species inhabiting the pine 
belt were noted. ‘The region embraced in the name of San Pedro 
-Martir consists of a high plateau of about sixty-five or seventy 
miles in length by twenty in width, lying about twenty miles 
from the gulf, and with its greatest extent parallel with that 
coast. Most of the plateau would be embraced within the limits 
of 30° and 31° north latitude. The northern end rises to a 
height, in one or two peaks, of 12,500 feet, estimated, and from 
that point the ridges and peaks drop away by degrees until at 
the southern end they merge into the low, barren hills, common 
to the peninsula at this point. The east and northern slopes, 
however, are very steep and rocky, with only two or three 
almost impassable trails, while the eastern side presents along its 
entire length in many places a sheer precipice for thousands of 
feet. : 
A series of large open meadows is found at an eleyation of 
8000 to 8500 feet, surrounded by rough, rocky ridges and heavy 
pine timber. These ridges are characteristic of the entire region 
which is composed of soft, friable syenite, the softer parts of 
which in crumbling away have left huge masses of gigantic 
boulders forming ridges, in many cases impassable. A growth 
of yellow pine, Pinus Jeffreyi, covers the ridges and slopes as low 
as 7000 feet altitude, where it gives place to a belt of scattered 
pifions, P. Parryana, reaching to 6000 feet or less, a growth of 
Manzanita and Ceanothus covers all of the slopes and ridges 
where it is too rocky for the pines to obtain a foot-hold, and in 
many places a small shrub oak was abundant. The streams, 
which were abundant, were all fringed with willow and a few 
Aspens were seen in some localities. Arising as this region 
