60 THE NATURAL HISTORY 



LETTER XIX 



Selbornb, Aug. 17, 1768. 

 Dear Sin, 



I have now, past dispute, made out three distinct 

 species of the willow-wrens (motacillse Irochili) which 

 constantly and invariably use distinct notes. But, at the 

 same time, I am obhged to confess that I know nothing 

 of your willow-lark. In my letter of April the 18th, I 

 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 its 

 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 

 grasshopper-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 rcgulus non cristatus of Ray, 

 which he says " canlal voce siriduld locustee." Yet this 

 great ornithologist never suspected that there were three 

 species. 



LETTER XX 



Selboune, October 6, 1768. 



It is, I find, in zoology as it is in botany : all nature is 

 so full, that that district produces the greatest variety 



