CO THE PHYSIOLOGY OF THE COMMON CRAYFISH. 



The cuticular lining wliicli gives rise to all the com- 

 plicated apparatus Avhicli has just been described, must 



Fig. 11. — AstacJis flnviatilis. — Yiew of the roof of the stomach, the 

 ventral wall of which, and of the mid-gut, is laid open by a longi- 

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

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

 pouch. The letters have the same signification as in fig. 10. 



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 



