i6 



THE LIFE OF CRUSTACEA 



old before moulting, is at first quite soft, and the 

 animal rapidly increases in size owing to the absorp- 

 tion of water. The shell then gradually hardens by 

 the deposition of lime salts. 



The internal anatomy (Fig. 6) presents many points 

 of interest which can only be briefly touched on here. 

 The food-canal consists of a short gullet leading into 

 a capacious stomach, from which the straight in- 



Ofiening of Hirer- cf act- 

 Optic Nerve 



\Brqin If^ 



^ Stomach. * \ 



Superior atraominZd artery 

 Intestine 



FIG. 6 DISSECTION OF MALE LOBSTER, FROM THE SIDE. (From 

 British Museum Guide.) 



testine runs to the vent on the under-side of the 

 telson. The stomach has a most remarkable and 

 complicated structure. It consists of two chambers, 

 a larger in front and a smaller behind, which are 

 lined by a continuation of the chitinous outside 

 covering of the body. This chitinous lining is 

 thickened in places to form a system of plates and 

 levers connected with three strong teeth set in the 

 nawow opening between the two chambers. By the 



