THE PIGEON. 223 



toneal investment of the gizzard : both layers are continued 

 backwards as the great omentum (§ i6i). 



186. The characters of the liver: its division into a 

 large right and a small left lobe : its free backwardly directed 

 ventral border : its anterior surface, hollowed out for the 

 reception of the heart : its posterior surface, hollowed by two 

 grooves on the right lobe for the duodenum, and by a deep 

 fossa on the left lobe for the gizzard. 



187. The gastro-hepatic omentum, a sheet of 

 peritoneum connecting the gizzard with the left lobe of 

 the liver. 



188. The mesogaster, a sheet of peritoneum connecting 

 the gizzard with the dorsal body wall. 



189. The mesentery, a greatly folded sheet of peritoneum 

 supporting the coils of the intestine, and connecting them 

 with the dorsal body wall. 



190. The posterior portion of the intestine, passing along 

 the middle line of the dorsal body wall towards the vent, 

 and suspended by a sheet of peritoneum, the meso- 

 rectum : about an inch in front of the vent are two small 

 lateral elevations, the caeca, on the walls of the gut, 

 marking the distinction between the small intestine 

 in front of them, and the large intestine or rectum 

 behind. 



191. The cloaca, a somewhat dilated chamber, open- 

 ing externally by the vent, and connected in front with 

 the rectum : its form and relations are best seen by inflating 

 with air from the vent. 



XXVIII. Dissect away the great omentum, turn for- 

 ward the lobes of the liver and dissect out the 

 following structures : 



192. The right bile duct, a delicate, whitish tube, 

 proceeding from the posterior surface' of the right lobe 



