24 



(c) A number of small oblique folds lie external to eacli 

 ventral fold. 



Tlie great width of a posterior section tlirougli tlie 

 gullet is due to its ventro-lateral extension into the 

 (esophageal pouches. These occupy part of the space at 

 the back of the buccal mass and are not sharply marked 

 off, being, as it were, mere bulgings of the gullet. The 

 lumen of each pouch is continued forwards into that part 

 of the gullet cavity lateral to the dorsal fold of its side. 

 The gullet is, to some extent, asym.metrical on account 

 of the shift to the left where it merges into the crop. 



The Crop (hgs. 10 and 18). — On passing into the 

 visceral mass the food tube shifts further to the left of 

 the median line and its walls become very much 

 thickened. This thick-walled region is called the croj?. 

 It is imbedded in the visceral mass and care is needed to 

 expose without damaging it. The buccal and digestive 

 glands adhere to its walls, and various gut coils also hide 

 it from view. In this imbedded position it runs back 

 some distance, becomes much narrower, and then passes 

 to the right and runs forward. 



The lining of the crop projects internally to form the 

 following folds : — 



[a] The continuations of the longitudinal dorsal folds 

 of the gullet. These folds pass down the left side of the 

 gut-wall and become mid-ventral, thus indicating that 

 the crop has been subjected to a torsion of 180° relative 

 to the head. Further back, these folds run up the right 

 side showing an additional torsion of 90^ or more 



(fig. m. 



(b) The continuations of the ventral longitudinal folds 

 of the gullet. These have fused basally, so we find a 

 single outgrowth branching distally into two. This keeps 

 at a uniform space of 180° from the dorsal folds and so 



