182 THE BIOLOGY OF THE ANIMAL 



1. The oesophagus. — What is its position? In 



which direction does it extend ? What is its 

 shape? Color? Notice the opening, the occip- 

 ital foramen, by means of which the cavity 

 of the head communicates with that of the 

 thorax. Note also the large muscles running 

 from the inner ends of the jaws up into the 

 head. To what are they attached ? 



2. The crop. — In what part of the body does it lie? 



What is its relation to the oesophagus? Shape? 

 Color ? Structure ? Examine its contents with 

 the microscope. What does it contain ? Look 

 for small salivary glands among the muscles 

 under the crop, and, if possible, trace the duct 

 which places the glands in communication with 

 the mouth. 



Hidden by the anterior ends of the gastric 

 coeca find 



3. The proventriculus or " gizzard." — Eelation 



to the crop? In what segments does it lie? 

 Shape? Structure? Color? 



4. The ventriculus or stomach. — Position ? 



Shape? How is it connected to the proven- 

 triculus ? Structure ? Color ? 



5. The gastric coeca. — What is their relation to 



the proventriculus and the ventriculus ? How 

 many are there ? What is their shape ? Struct- 

 ure ? Color ? With what do they connect ? 



6. The ilium. — Eelation to the ventriculus ? How 



long is it ? What is its shape ? Color ? Struct- 

 ure ? In what direction does it run ? Do you 

 find in it anything resembling a valve ? 



At the junction of the stomach and ilium 

 look for 



