PHYLUM ARTHROPODA 



231 



the appendages, and the essential features of the internal 

 anatomy. The crabs and the hermit-crabs differ from the 

 other forms mentioned, mainly in the abdomen being re- 

 duced. In the crabs (Fig. 131) this region is extremely 

 small, its appendages are only feebly developed, and it is 



FIG. 132. Pagurus bernhardus. ch, chela of first right leg; /. 4, 1. 5, fourth and 

 fifth legs; t, abdominal terga; up, uropods. (After Bell.) 



permanently flexed on the sternal surface of the cephalo- 

 thorax, so that it is completely concealed from view when 

 the animal is looked at from above. 1 In the hermit-crabs 



1 The European Cancer is represented by our common Cancer irro- 

 ratus, and the explanation of Fig. 131 will equally well apply to our species. 



