146 



GENERAL ZOOLOGY 



The blue crab is not confined to the salt water, for it is 

 found frequently in rivers some distance from bays. Wherever 

 they are, they devour much of the organic waste that is carried 

 down to the sea. They are therefore important as scavengers. 

 The most noticeable feature in the structure of the fiddler- 

 crab (U'ca pugila'tor, Fig. 72) is the presence in the males of 

 a large cheliped. Sometimes it is the right one that is larger, 



and sometimes the left one ; the 

 females have their chelipeds small 

 and of equal size. 

 The name " fiddler" 



<^< ' 



FIG. 72. Fiddler-Crab. Slightly reduced 



is supposed 

 to have been 

 derived from the 

 fancied resemblance of 

 the large cheliped to a 

 fiddle, and of the small 

 one to a bow. 



Fiddler-crabs live in 

 the mud and sand of salt-marshes along the Atlantic coast. 

 Sometimes on the higher ground where the sand is cleaner 

 and drier, and where vegetation is scant, these crabs may be 

 observed by the cautious visitor, as they glide quietly out 

 of their holes bearing pellets of sand and gravel under their 

 legs and cephalothorax, to deposit the burden a foot or more 

 away from their holes. The species shown in the picture has 

 been observed to carry on this process of excavation in the 



