NATURAL SCIENCES OE PHILADELPHIA. 
301 
nearly with the measurements.* I think, then, that there can he no reason- 
able doubt of the propriety of referring the large northern specimens to the 
arg entatoides of Richardson and Bonaparte. These same specimens were, 
immediately upon their reception, referred unhesitatingly to Californicus of 
Lawrence, by both Prof. Baird and myself. We have critically examined 
them, and find it impossible to distinguish them from undoubted specimens 
of Californicus. 
The size is somewhat greater ; but not more so than would be expected 
from the much more northern habitat of the specimens examined ; and, more- 
over, the numerous specimens differ among themselves to a remarkable de- 
gree, the smallest of the northern ones not exceeding the largest of the 
southern. Thus, though a large northern bird and a small southern differ so 
much that it would seem quite reasonable to separate them, there are found 
intermediates of every grade of dimensions. The upper parts of the northern 
bird are, perhaps, a shade lighter than are California specimens ; but other- 
wise, we cannot appreciate the slightest distinctive characters. Now, it is not 
improbable that there should be in America two species of white-tipped pri- 
maried Gulls, the one from Arctic (and Eastern ?f) America and the other 
from the Pacific, differing from each other, on an average, in size ; but in the 
absence of tangible characters, I do not venture to separate the two. I there- 
fore, at present, quote “ Larus argentatoides, Bp. et Rich, nec Brehm” as 
synonymous with “ Californicus, Lawr.,” leaving it to future investigation to 
settle the point definitely. 
The only discrepancy to be reconciled in the description of Richardson, is 
the statement “legs flesh-colored.” The legs of Californicus are of a dusky 
olivaceous greenish or yellowish, their interdigital membranes bright chrome 
yellow, with a slight tinge of green. In this respect, as well as in a general 
less powerful and robust organization, weaker bill, &c., it shows an evident ap- 
proach to the “Mew-Gulls” fDelawarensis , canus , &c. ), and apparently forms 
the connecting-link between the powerful Herring- Gulls, with their robust 
bills and flesh-colored legs, and the group of which canus is the type.:}: Hut 
Mr. Lawrence himself, in his description given in the General Report, says 
also “legs flesh-colored,” though the color is given correctly in the Ann. N. 
Y. Lyc. N. H. The descriptions of both these authors were most probably 
drawn up from the dried skins, in which, as attested by a large series before 
me, the legs appear of a dingy undefinable color, which might readily be sup- 
posed to be the change produced in drying of the flesh color. My authority 
for the statement as to the color of the legs, is the labels attached to the 
specimens, containing the color of bills, eyes, legs, &c., taken from the recent 
bird before skinning. 
The type of Californicus has been kindly furnished by Mr. Lawrence for 
examination. It is moulting, and some of the primaries are not fully grown 
out. The white apical space on the first primary is interrupted by a narrow 
transverse bar of black. Another specimen before me is in precisely the 
same condition. In other skins of the series the black bar is resolved into 
not take into special consideration the character of the extent of the bluish white bases 
of the quills; and since the black nearly occupies the whole of the outer web of the 
first, he would not have particularly noticed the extent to which the bluish white runs 
up on the inner vane. 
* I am inclined to think that Richardson drew up his measurements and descriptions 
from the largest as well as the most perfect specimens, since, in several instances, the 
measurements seem above the average, though not exceeding the dimensions of large 
individuals. 
t Bonaparte (Syn., 1828, 360) says his argentatoides is “ common near New York and 
Philadelphia.” 
t This fact is also an argument for the impropriety of separating the two groups gene 
rically, as has been done by some authors. 
1862.] 
