228 NATVRAL HISTORY 



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 goat-sucker, 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 

 aabit and shape, we suspected might resemble the cuckoo 

 in its internal construction. Nor were our suspicions ill- 

 grounded; for upon the 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 Phalcence 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 practise incubation, is formed in a similar manner with 

 cuckoos, Monsieur Herissant's conjecture that cuckoos are 

 incapable of incubation from the disposition of their intes- 

 tines 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 Cuculus canorus. 1 



We found the case to be the same with the ring-tail hawk 2 

 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. 



1 The cuckoo has no true crop, and the position of its proventriculus 

 does not differ from that of other scansorial birds ; the oesophagus de- 

 scends along the posterior or dorsal part of the thorax, inclining to the 

 left side, and, when opposite to the lower margin of the left lung, it 

 begins to expand into the glandular cavity or proventriculus. The giz- 

 zard, which is neither large nor strong, is in immediate contact with the 

 abdominal parietes, and not separated from them by an intervening 

 stratum of intestines ; but this position cannot be supposed to interfere 

 with the power of incubation, since it occurs also in other birds that du 

 incubate. ED. 



2 This is a provincial name for the female Hen harrier, Circus cyaneus 



