96 Brewster on a Petrel new to North America. 
family. This is PEstrelata defilippiana, described* by Drs. 
Giglioli and Salvadori from four specimens taken off the coast of 
Peru in lat. 1 8° 4' S., long. 79 0 35' W. 
In comparing their supposed species with PE. gularis “as de- 
scribed by Coues” the joint author’s remark; “But our species 
differs .... in its smaller dimensions and slighter make {PE . gularis 
being in size and make similar to PE. mollis ) , in the cinereous 
coloration of its upper, and the pure white of its lower parts, 
while PE. gularis would be dark-colored above and below hav- 
ing only the tail-coverts white.” PE. defilippiana also “ has a 
bill relatively, and in some specimens, absolutely longer.” 
But these color-differences lose much of their significance when 
it is remembered that the bird “described by Coues” was the 
young of gularis. My more mature specimen agrees very closely 
with their description save that it is not “ subtus omnino pure 
alba ” ( this__ is afterwards slightly qualified by “ later ibus pectoris 
vix cinereo-tinctis”}, — and it is by no means improbable that 
the fully adult gularis will be found to have the under parts 
wholly white.f 
The discrepancy in size is less easily reconciled. The birds 
examined by Drs. Giglioli and Salvadori are all apparently smaller 
than either of the known examples of gularis. But still the 
largest of the former approaches suspiciously close to the smaller 
of the two latter : — PE. defilippiana , wing, 9.45 ; PE. gularis , 
do., 9.80:— and furthermore, in respect to individual size, the 
Petrels are notoriously variable. Nor can a comparison of 
measurements taken by different persons always be relied upon. 
Different methods give widely divergent results.! Scarcely two 
* “ On some new Procellariidas collected during a voyage around the world in 1865-68 
by H. I. M.’s S. ‘ Magenta.’ By Henry Hillyer Giglioli, Sc. D., C. M. Z: S., Naturalist 
to the expedition, and Thomas Salvadori, M. D., C. M. Z. S., Assistant in the Royal 
Zoological Museum of Turin,” Ibis 1869 pp. 63-65. 
Rowley also gives a superb figure of the bird in his Ornithological Miscellany (Vol. I ; 
p. 255, pi. xxxiii) but adds nothing new to an account taken from the text of the Ibis 
article. 
f In speaking of the young of mollis Dr. Coues says : “ The whole under parts 
are not notably different from the back, though, however, the dark color only occupies 
the tips of the feathers; their basal moiety remaining white." This statement is signifi- 
cant in this connection, for upon examining my specimen, I find that the plumbeous 
color below, and also on*certain parts of the head and neck, is mainly confined to the 
tips of the feathers, their concealed portions being snowy-white. 
! Since writing the above I find a curiously apropos illustration of this. In Peale’s 
original description of the type specimen the “ wing from the carpal joint” is given as 
“ ten and a half inches ” while my measurement of the same bird made it 9.80, a differ- 
ence of nearly three quarters of an inch. 
