132 NATURAL HISTORY OF SELBORNE. 
they are not to pair and discharge their parental functions till the 
ensuing spring/' As colours seem to be the chief external sex- 
ual distinction in many birds, these colours do not take place till 
sexual attachments begin to obtain. And the case is the same 
in quadrupeds ; among whom, in their younger days, the sexes 
differ but little : but, as they advance to maturity, horns and 
shaggy manes, beards and brawny necks, &c. &c. strongly dis- 
criminate the male from the female. We may instance still fur- 
ther in our own species, where a beard and stronger features are 
usually characteristic of the male sex : but this sexual diversity 
does not take place in earlier life ; for a beautiful youth shall 
be so like a beautiful girl that the difference shall not be dis- 
cernible ; 
Quern si puellarum insereres choro, 
Mird sagaces falleret hospites 
Discrimen obscurum, solutis 
Crinibus, ambiguoque vultu." Hor. 
LETTER VII. To the Hon. DAINES BARRINGTON. 
DEAR SIR, Ringmer, near Lewes, Oct. 8, 1770. 
I AM glad to hear that Kuckalm is to furnish you with the birds 
of Jamaica ; a sight of the hirundines of that hot and distant island 
would be a great entertainment to me. 
The Anni of Scopoli are now in my possession : and I have 
read the Annus Primus with satisfaction : for though some parts 
of this work are exceptionable, and he may advance some mis- 
taken observations, yet the ornithology of so distant a country 
as Carniola is very curious. Men that undertake only one dis- 
trict are much more likely to advance natural knowledge than 
those that grasp at more than they can possibly be acquainted 
with : every kingdom, every province, should have its own mo- 
nographer. 
The reason perhaps why he mentions nothing of Ray's Orni- 
thology may be the extreme poverty and distance of his country, 
into which the works of our great naturalist may have never yet 
found their way. You have doubts, I know, whether this Orni- 
thology is genuine, and really the Avork of Scopoli : as to myself, 
I think I discover strong tokens of authenticity ; the style cor- 
responds with that of his Entomology : and his characters of his 
