THE DIGESTIVE SYSTEM. 65 



CBSophagug appears dilated in each segment, and 

 constricted where it perforates the septa. 



a. The oesophageal pouches are a pair of short lateral 



diverticula of the oesophagus lying in segment x., 

 and opening into the oesophagus at the anterior 

 end of segment xi. At certain seasons they con- 

 tain concretions of more or less crystalline cal- 

 careous matter, chiefly calcium carbonate. 



To see these ossophageal f ouches, press aside the large white 

 vesiculcB seminales which hide them. 



b. The oesophageal glands are two pairs of lateral 



protuberances on the sides of the oesophagus in 

 segments xi. and xii. They are hollow, and their 

 cavities, which are subdivided by a large number 

 of horizontal lamellae, contain a milky calcareous 

 fluid. They are local thickenings of the glan- 

 dular walls of the oesophagus, and their nume- 

 rous cavities open into the oesophageal pouches. 



4. The crop is a large dilated portion of the alimentary 



canal in segments xiii. to xvi., but when filled it en- 

 croaches upon the segments in front, pushing the 

 septa before it (fig. 23). 



5. The gizzard extends from the sixteenth segment back- 



wards to about the twentieth. Its walls are very 

 thick and muscular, and it has a thick chitinous 

 lining. 



6. The intestine is a thin-walled sacculated tube running 



straight backwards from the gizzard to the anus. 



a. The ' hepatic cells ' are a layer of yeUow peritoneal 



cells Surrounding the intestine and in close rela- 

 tion with the blood-vessels. 



Cut the intestine open along one side, and ivash out its 

 contents. 



b. The typhlosole is a prominent median longitudinal 



ridge projecting into the cavity of the intestine 



F 



