WILLOW-LARK. 65 



to take in fresh air. I opened a big-bellied one, 

 indeed, and found it full of spawn. Not that this 

 circumstance at all invalidates the assertion that 

 they are larva: for the larvts of insects are full of 

 eggs, which they exclude the instant they enter 

 their last state. The water-eft is continually climb- 

 ing over the brims of the vessel, within which we 

 keep it in water, 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 1 . 



XIX. 



I HAVE now, past dispute, made out three 

 distinct species of the willow-wrens, (motacillce 

 trochili,) which constantly and invariably use 

 distinct notes. But, at the same time, I am 

 obliged to confess that I know nothing of your 

 willow-lark 2 . In my letter of April the 18th, 

 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 



1 The fins, or membrane on the tail and back, increase 

 greatly at the season of generation ; at other times they are 

 hardly perceptible. W. J. 



* Brit. Zool. edit. 1776, octavo, p. 38L 



F 



