GEOGRAPHICAL SURVEYS WEST OF DOTH MERIDIAN. 291 
Cotyle Boie. 
C. riparia. Bank Swallow. 
Present in Ijevada anti Eastern California, but apparently less numerous than the 
following. 
Stelgidopteryx Baird. 
S. serripennis (Aud.). Rough-winged Swallow. 
According to Cooper and Suckley, this swallow occurs as far to the north on the 
coast as Puget Sound; certaiuly present along much of the eastern slope, and doubt¬ 
less extending into Washington Territory along this line. 
Progxe Boie. 
P. subis (L.). Purple Martin. 
Colonies encountered at numerous localities among the pine woods of the mountains, 
where they are quite local. 
YIREONID.E—Greenlets. 
Vireo Vieillof. 
V. gilvus sivainsoni Bd. Western Warbling Vireo. 
This vireo was found to be present along the eastern slope as far north as Southern 
Oregon, and, as I have never seen it more abundant than it was in Northern California, 
I have no doubt that it reaches to the Columbia along this line, or even into Washing¬ 
ton Territory, as it does, according to Cooper and Suckley, along the Pacific side. 
Very little can be said of its habits here that would not be a repetition of published 
accounts of the Eastern -warbling vireo. It is merely that bird transferred from its 
usual surroundings to the wild mountain districts of the west. In the mountains near 
Camp Bidwell, the locality alluded to above, where the species was so numerous, I 
found many nests, three or four being often met with during a morning’s collecting. 
They were without exception built upon small aspen trees, from three to five feet 
above the ground. With a lining of fine grasses, they were composed mainly of long 
strips of white fibrous bark, festooned externally with spiders’ webs, bits of cottony 
substances from plants, &c. At this date, July 20-30, the eggs were so far advanced 
as to render their preservation very difficult. 
Vireo 8olitariu8 cassini Xantus. Cassin’s Vireo. 
Few birds have given rise to more perplexing doubt and uncertainty respecting 
their relationships than the Cassin’s vireo. Founded by Xantus fin 1859, upon a fall 
specimen from Fort Tejon, its subsequent written history has been full of vicissitudes; 
for while by some authors it has been accepted as a valid species, by others it has 
been affiliated with solitarius as a variety; or, again, has been rejected altogether, and 
thrown into the list of synonyms of the latter bird. 
From the time I made the acquaintance of this vireo in the southern Rocky Moun¬ 
tains it has had a peculiar interest for me, more especially, perhaps, from the'fact 
that while then, and upon the many subsequent occasions I have met with it, I have 
had not the slightest difficulty in properly identifying the recently killed specimens 
or even the live birds ; yet, in the closet and upou comparison with other specimens 
from the West marled as solitarius, I have found it extremely difficult to draw a line be¬ 
tween the two; in fact, until the present time I have never been able to arrive at any satis¬ 
factory conclusion respecting the true rank of cassini and its kinship to solitarius. I am 
now fully persuaded, and trust to be able to show, that cassini is at the least something 
more than a special plumage of solitarius, which was the opinion expressed by Professor 
Baird in his Review of North American Bh'ds, when, it is to be remembered, the type- 
specimen represented all that was known of the supposed species, the absence of ma¬ 
terial for comparison doubtless having much to do in shaping this view. Since then 
there have accumulated in the Smithsonian, as the result of the collections of this 
expedition and from other sources, twelve or more specimens that are either like the 
original type of cassini, or so near it that their identity with it is beyond suspicion. It 
is perfectly safe to say that, whatever it is, they are. 
With little or no difference in size from Eastern solitarius, the type—and it is to be 
remarked that certain of the recently obtained specimens not only share its peculiari¬ 
ties but even exhibit them to a greater degree—offers only differences of coloration. 
These maybe briefly summed up as follows: Typical examples of cassini are very 
much duller than the corresponding plumages of solitarius. The head above and on 
the side, instead of beiug of a decided blue or bluish ash, presents little or absolutely 
no contrast to the olive-brown (instead of olive-green) of the dorsum. The lores and 
