OF SELBOENE 45 



and wandering away : and people every summer see numbers 

 crawling out of the pools where they are hatched, up the dry 

 banks. There are varieties of them, differing in colour; and 

 some have fins up their tail and back, and some have not.^ 



LETTER XIX. 



TO THE SAME. 



Dear Sir, 



Selborne, Aug. 17, 1768. 



I HAVE now, past dispute, made out three distinct species of the 

 willow-wrens (motacillce Irochili) which constantly and invariably 

 use distinct notes. But, at the same time, I am obliged to con- 

 fess that I know nothing of your willow-lark.^ In my letter of 

 April the 1 8 th, I had told you peremptorily that I knew your willow- 

 lark, but had not seen it then : but, when I came to procure it, 

 it proved, in all respects, a very motacilla trochilus ; only that it 

 is a size 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 specimens of the three sorts now lying 

 before me ; and can discern that there are three gradations of 

 sizes, and that the least has black legs, and the other two flesh- 

 coloured ones. The yellowest bird is considerably the largest, 

 and has it's quill-feathers and secondary feathers tipped with 

 white, which the others have not. This last haunts only the 

 tops of trees in high beechen woods, and makes a sibilous grass- 

 hopper-like noise, now and then, at short intervals, shivering a 

 little with its wings when it sings ; and is, I make no doubt now, 

 the regulus non cristatus of Ray ; which he says " cantat voce striduld 

 locustcB ". Yet this great ornithologist never suspected that there 

 were three species.' 



1 [In the breeding season the males of several species of triton have fins along 

 the tail and back, which are not found at other times.] 



2 Brit. Zool. edit. 1776, octavo, p. 381. 

 ' [See note to p. 36.] 



