i LL 
SHARP-SHINNED HAWK. 531 
judged from a single very fine specimen; but the scales are equally 
distinct in all the younger individuals of the A. Pennsylvanicus, although 
in one, an old male, the distinctions between the greater number are 
obliterated, so that they resemble a single plate. There is nothing 
very remarkable in this, however. for the like happens to other Hawks ; 
it having been long ago remarked with regard to the Sparrow Hawk of 
Europe, Accipiter Nisus, that “in some individuals, the anterior ob- 
lique scutella, as well as the hexagonal scales of the sides, are so 
indistinct, that all traces of them disappear when the parts become 
dry.” 
Accipiter Nisus, A. velox, and A. Mexicanus, which are most closely 
allied, insomuch that it is extremely difficult to distinguish them from 
each other, may be characterized as follows :— 
A. Mexicanus is largest ; has the fifth quill longest, the first primary 
much longer than the last, the tail distinctly rounded, the tarsi stouter, 
and with fifteen scales; the upper parts deep slate-blue ; the lower 
banded with light red and white. 
A. velox is smallest, has the fourth quill longest, the first primary 
much shorter than the last, the tail even, the tarsi extremely slender, 
with fifteen scales ; the colours exactly as in Mexicanus. 
A. Nisus is intermediate in size, never so small as velox, but some- 
times as large as Mevicanus, with the fourth quill longest, the first and 
last primary about equal, the tail very slightly rounded or even, the 
tarsi very slender, with eighteen scales, the upper parts deep slate-blue, 
the lower narrowly banded with light red in the male, and dusky in the 
female. 
This species was described by Witson under the name of Sharp- 
shinned Hawk, Falco velox, and figured in Pl. XLV, a young female 
only being represented, although a description is given of a young 
male also. He afterwards feared an adult male (Pl. XLVI), and de- 
scribed it under the name of Slate-coloured Hawk, Falco Pennsylva- 
nicus, considering it as a distinct species. It appears, however, that it 
had previously been described under several names. ‘Thus Falco fuscus 
of Mritter and Gme.in, and the American Brown Hawk of Laruam, 
seem to be the same bird in the young state. Falco dubius of GMELIN 
and Latuam, the Dubious Falcon of the latter and of PENNANT are also 
