66 NATURAL HISTORY OF SELBORNE. 



LETTER XXIII. 



TO THE SAME. 



SELBORNE, Feb. z%th, 1769. 



DEAR SIR, It is not improbable that the Guernsey lizard and 

 our green lizards may be specifically the same ; all that I know is, 

 that, when some years ago many Guernsey lizards were turned loose 

 in Pembroke college garden, in the University of Oxford, they 

 lived a great while, and seemed to enjoy themselves very well, but 

 never bred. Whether this circumstance will prove anything either 

 way I shall not pretend to say. 



I return you thanks for your account of Cressi Hall ; but recol- 

 lect, not without regret, that in June 1746 I was visiting for a week 

 together at Spalding, without ever being told that such a curiosity 

 was just at hand. Pray send me word in your next what sort of 

 tree it is that contains such a quantity of herons' nests ; and 

 whether the heronry consists of a whole grove of wood, or only of 

 a few trees. 



It gave me satisfaction to find we accorded so well about the 

 caprimulgus ; all I contended for was to prove that it often chatters 

 sitting as well as flying ; and therefore the noise was voluntary, 

 and from organic impulse, and not from the resistance of the air 

 against the hollow of its mouth and throat. 



If ever I saw anything like actual migration, it was last Michael- 

 mas Day. I was travelling, and out early in the morning ; at first 

 there was a vast fog; but, by the time that I was got seven or 

 eight miles from home towards the coast, the sun broke out into a 

 delicate warm day. We were then on a large heath or common, 

 and I could discern, as the mist began to break away, great num- 

 bers of swallows (Jiirundines rustical) clustering on the stunted 

 shrubs and bushes, as if they had roosted there all night. As soon 

 as the air became clear and pleasant they all were on the wing at 

 once ; and, by a placid and easy flight, proceeded on southward 

 towards the sea ; after this I did not see any more flocks, only new 

 and then a straggler. 



I cannot agree with those persons that assert that the swallow 

 kind disappear some and some gradually, as they come, for the 



