88 NATURAL HISTORY OF SELBORNE. 



following instance, I cannot help being inclined to think it 

 may conduce towards the explanation of a difficulty that I have 

 mentioned before, with respect to the invariable early retreat of 

 the hirundo apus, or swift, so many weeks before its congeners ; 

 and that not only with us, but also in Andalusia, where they also 

 begin to retire ab Hit the beginning of August. 



The great large bat (which by-the-by is at present a non- 

 descript in England, and what I have never been able yet to 

 procure) retires or migrates very early in the summer ; it also 

 ranges very high for its food, feeding in a different region of the 

 air ; and that is the reason I never could procure one. Now this 

 is exactly the case with the swifts ; for they take their food in a 

 more exalted region than the other species, and are very seldom 

 seen hawking for flies near the ground, or over the surface of the 

 water. From hence I would conclude that these hirundines and 

 the larger bats are supported by some sorts of high-flying gnats, 

 scarabs, or phalana, that are of short continuance ; and that the 

 short stay of these strangers is regulated by the defect of their 

 food. 



By my journal it appears that curlews clamoured on to 

 October 3ist; since which I trve not seen nor heard any. 

 Swallows were observed on to November 3rd. 



LETTER XXVII. 



SELBORNE, Feb. 22nd, 1770. 



DEAR SIR, Hedgehogs abound in my gardens and fields. 

 The manner in which they eat the roots of the plantain in my 

 grass-walks is very curious ; with their upper mandible, which is 

 much longer than their lower, they bore under the plant, and so 

 eat the root off upwards, leaving the tuft of leaves untouched. 

 In this respect they are serviceable, as they destroy a very 

 troublesome weed ; but they deface the walks in some measure 

 by digging little round holes. It appears, by the dung that they 



