OF SELBORNE. 55 
of April the 1 8th, I had told you peremptorily that I knew your 
willow-lark, but had not feen it then : but, when I came to pro- 
cure it, it proved, in all relpefts, a very motacilla trochilus ; only 
that it is a fize larger than the two other, and the yellow-green 
of the whole upper part of the body is more vivid, and the belly 
of a clearer white. I have fpecimens of the three forts now lying 
before me; and can difcern that there are three gradations of fizes, 
and that the leaft has black legs, and the other two flelh-coloured 
ones. The yelloweft bird is confiderably the largeft, and has it's 
quill-feathers and fecondary feathers tipped with white, which 
the others have not. This lafl haunts only the tops of trees in 
high beechen woods, and makes a fibilous grafshopper-like noife, 
now and then, at fliort intervals, fliivering a little with it's wings 
when it fings ; and is, I make no doubt now, the regulus non. 
criftatm of Ray\ which he fays cantat voce JlriduUi locufite" Yet 
this great ornithologifb never fufpedted that there were three 
fpecies. 
LETTER XX. 
TO THE SAME. 
Selborne, Oilober 8, 1768. 
It is, I find, in zoology as it is in botany: all nature is fo full, 
that that diftri(ft produces the greateft variety which is the moft 
examined. Several birds, which are faid to belong to the nordi 
only, are, it feems, often in the fouth, I have difcovered this 
fummer 
