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 
Fig. 11.—Astacus fluviatilis—View 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 lat * tnoth 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 
