60 THE PHYSIOLOGY OF THE COMMON CRAYFISH. 



The cuticular lining which gives rise to all the com- 

 plicated apparatus which has just been described, must 



Fia. ll.-A^acns Jiuriatms.-y\^ of the roof of the stomach the 

 ventral wall of which, and of the mid-gut, is laid open '^l^^2rl^ 

 tudinal incision ( x 4). On the right side (the left in the » 

 the lateral tooth is cut away, as well as the floor of the lateral 

 pouch. The letters have the same signification as m fag. lU. 



not be confounded with the proper wall of the stomach, 

 which invests it, and to which it owes it origin, just as 

 the cuticle of the integument is produced by the soft 



