NATURAL HISTORY OF SELBORNE. 211 



very uneasy situation during the business of incubation ; yet the 

 lest 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 habit 

 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 phatcentz, 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 

 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 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 cuculus 

 cancrus. 



We found the case to be the same with the ring-tail 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. I am, etc. 



LETTER XXXI. 



SELBORNE, April 2tyh, 1776. 



DEAR SIR, On August 4th, 1775, we surprised a large viper, 

 which seemed very heavy and bloated, as it lay in the grass bask- 

 ing in the sun. When we came to cut it up, we found that the 

 abdomen was crowded with young, fifteen in number ; the shortest 

 of which measured full seven inches, and were about the size of 



