90 
NATUB.AL HISTORY 
Though I delight very little in analogous reasoning, 
knowing how fallacious it is with respect to natural history ; 
yet^ in the following instance, I cannot help being inclined 
to think it may conduce towards the explanation of a diffi- 
culty 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 j^\ndalusia, where they also begin to retire 
about the beginning of August. 
The great large bat^ (which by the by is at present a 
nondescript 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 highflying gnats, 
scarabs, or Phalcence, 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 the thirty-first ; since which I have not seen or 
heard any. Swallows were observed on to November the 
third. 
^ The little bat appears almost every month in the year ; but I have 
never seen the large ones till the end of April, nor after July. They 
are most common in June, but never in any plenty ; are a rare species 
with us. — G. W. 
2 Stone-curlews, CEdicnemus crepitans. The true curlew, Numenius 
arcuutus, was not observed at Selborne. — Ed. 
