TOO 



THE BIOLOGY OF BIRDS 



of the Hoatzin of Brazilian swamps, a bird to which he has 

 given special attention. The crop has become exaggerated 

 at the expense of the stomach, and it has strong muscles in 



Fig. 24. — Dissection of pigeon's food-canal, etc. From a specimen. 

 I, gullet ; 2, windpipe ; 3, crop ; 4, song-box ; 5, lung ; 6, liver ; 7, pro- 

 ventriculus part of stomach ; 8, part of liver ; 9, part of small intestine ; 

 10, gizzard; 11, 15, pancreas; 12, 13, two ducts of pancreas; 14, 

 duodenum ; 16, small intestine ; 17, testis ; 18, 22, rectum ; 19, kidney ; 

 20, vas deferens or duct of testis; 21, ureter or duct of kidney; 

 23, cloaca. The heart was removed. 



