104 THE ZOOLOGIST. 
ON SEXUAL DIFFERENCES IN THE FEATHERING 
OF THE WING OF THE SKY LARK (ALAUDA 
ARVENSIS). 
By ArtHur G. Burier, Ph.D., &e. 
In Volume II. of ‘ British Birds with their Nests and Eggs’ 
(p. 174), I have noted the fact that bird-dealers recognise cock 
Sky Larks, by the greater length of the second primary of the 
wing in that sex. I had intended to illustrate the well-defined 
sexual differences in this species by a process-block (i. c.), as I did 
in the case of the Linnet, but unhappily when the wings were 
needed Mr. Frohawk was utterly unable to obtain examples 
for illustration, whilst at that time I possessed the male wing 
only. 
I now have before me eight wings, four of which (two right- 
hand wings of each sex) were secured, mounted, and kindly given 
to me by Mr. C. H. B. Grant, who shot these and other birds 
last December in Hampshire. 
The wing of the male Sky Lark, as I have already stated 
elsewhere, is especially adapted for powerful and sustained flight, 
whereas that of the female is altogether weaker in construction ; 
indeed, so greatly do the wings differ in old birds that a glance 
would enable the dullest observer to decide their sex; even in 
young birds the distinctions are well marked. 
As is well known, the first primary in the Sky Lark (as in 
many Passerine birds) is very small; so that by a superficial 
observer it might easily be confounded with the coverts. The 
second, third and fourth primaries are, however, the longest in 
the wing, and in the male Sky Lark these three feathers terminate 
almost at the same level; thus when superposed there is hardly 
any noticeable difference, though the third primary is very © 
slightly the longest. In the female the second primary is decidedly 
the shortest of the three and either the third or the fourth the 
longest, these three feathers in the female thus either forming an — 
