THE NATURAL HISTORY OF SELBORNE. 181 
berries, or some such fruit; so that these birds apparently 
subsist on insects and fruits ; nor was there the least appear- 
ance of bones, feathers, or fur, to support the idle notion of 
their being birds of prey. 
It must be allowed, as this anatomist observes, that the crop 
placed just upon the bowels must, especially when full, be 
in a very uneasy situation during the business of incuba- 
tion ; yet the test will be to examine whether birds that are 
actually known to sit for certain are not formed in a similar 
manner. This inquiry I proposed to myself to make with a 
fern-owl, or goatsucker, as soon as opportunity offered: 
because, if their formation proves the same, the reason for 
incapacity in the cuckoo will be allowed to have been taken up 
somewhat hastily. 
. Not long after a fern-owl was procured, which, from its 
habit and shape, we suspected might resemble the cuckoo 
in its internal construction. Nor were our suspicions ill- 
grounded ; for, upon dissection, the crop, or craw, also lay 
behind the sternum, immediately on the viscera, between them 
and the skin of the belly. It was bulky, and stuffed hard with 
large Phalene, moths of several sorts, and their eggs, which no 
doubt had been forced out of those insects by the action of 
swallowing. 
Now, as it appears that this bird, which is so well known to 
practice incubation, is formed in a similar manner with cuckoos, 
Monsieur Hérissant’s conjecture, that cuckoos are incapable of 
incubation from the disposition of their intestines, seems to 
fall to the ground ; and we are still at a loss for the cause of 
that strange and singular peculiarity in the instance of the 
common cuckoo. 
We found the case to be the same with the ring-tailed hawk, 
in respect to formation ; and, as far as I can recollect, with the 
swift ; and probably it is so with many more sorts of birds 
that are not granivorous. 
