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 puellariim insereres choro, 
Mire sagaces falleret hospites 
Discrimen obscurum, solutis 
Crinibus, ambiguoque vultu." Hor. 
LETTER VII. To the Hon. DAINES BARRINGTON. 
DEAR SIR, Rinc/mer, 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 work 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 
