5^ 



CRUSTACEA. 

 Macroura. 



This division, to which the lobster belongs, has already 

 received its full share of attention, and need not be 

 mentioned except so far as is necessary to show that 



Pig. 24. 



Astacus fluviatilis (after Morse 

 I 'r.iyfish. 



its proper position in the classification is in close asso- 

 ciation with the highest group of the Crustacea, the 

 Brachyura, common edible crabs and the like. 



Brachyura. 



We now pass to the crabs proper, or to the highest 

 of Crustacea. Figs. 25-27 represent our commonest 

 species of the genus Cancer. By this time the pupils 

 ought to detect similarities with readiness, and find no 

 great difficulty in comparing the crab and the lobster. 



The abdomen, the first ring of which is seen from 

 above (Fig. 25, ab 1), and all the rings from below 



