AND THEIR FUNCTIONS. 161 



raven, crow, quail, and owl, and his statements show that 

 he was aware that the proventriculus was well-developed in 

 the first three birds, and that, in the owl, it was but little 

 wider than the oesophagus. 



He says correctly that most birds have a fleshy and 

 compact gizzard, with an inner, strong skin separable from 

 the fleshy part.* He knew well the intestinal caeca of birds, 

 and states correctly that they are found in most birds, are 

 few in number, and are situated towards the termination of 

 the intestines.! It seems strange that, while he attempts 

 to give the numbers of the caeca in fishes, he merely says 

 that those of birds are few in number. The cseca in birds 

 are, as is now well known, almost always two. 



He must have examined the alimentary canal of many 

 birds, but he seems to have examined that of the quail with 

 more than usual care. According to him, this bird has a 

 well-marked proventriculus, and a crop which is at a great 

 distance from the gizzard, considering the small size of the 

 bird.! 



The proventriculus of the quail is close to the gizzard, 

 and, when gently inflated, about four-tenths of an inch in 

 diameter at its widest part, while the diameter of the oeso- 

 phagus is about three-tenths of an inch. Its crop is a 

 compact oval bag, and in one quail I found it to be 1"8 inches 

 from the gizzard, which seemed to be a great distance, 

 considering the size of the bird. 



He states incorrectly that, in most fishes, the stomach 

 is connected directly to the mouth, and that, on this 

 account, the stomach falls forward into the mouth when 

 they pursue smaller fishes. § 



The phenomenon described here, but incorrectly ex- 

 plained, occurs more especially in fishes having an air 

 bladder which does not communicate by means of a duct 

 with the alimentary canal. When a fish passes quickly or 

 is drawn from deep water towards the surface, the gas in 

 its bladder expands, and may tear the bladder and even the 

 mesentery and cause the anterior part of the alimentary 

 canal to project into the fish's mouth. 



The nature of the stomach and intestines in fishes is, 

 he says, similar to that in snakes, for fishes have a simple 

 stomach of different form in different fishes, for some have 



* H. A. ii. c. 12, s. 15. f Ibid. ii. c. 12, s. 17. 



X Ibid. ii. c. 12, ss. 15 and 17. § Ihid. ii. 12, s. 4. 



M 



