106 



ZOOLOGY 



respect to the length of their abdomen. The abdomen is 

 soft, and the animal protects it by inserting it within the 

 coiled shell of some gastropod. Moreover, the abdomen is 

 asymmetrical, being coiled to one side to correspond with 

 the shape of the borrowed house (Fig. 99). The abdominal 

 feet become degenerate, with the exception of the posterior 

 pair, which are modified into a hook-like process, by means 

 of which the crab maintains itself securely in the shell. 



FIG. OS. 



Eupagunis longicarpus. Two individuals in shells. Photo, while 

 alive by W. H. C. P. 



When one shell becomes too small, it is abandoned for a 

 larger one. Numerous species of hermit-crabs occur on 

 our coast, ranging from the shore line to a depth of several 

 hundred fathoms. Eupagurus longicarpus is the little 

 active hermit found in almost any tide-pool from Massa- 

 chusetts Bay to the Gulf of Mexico. Hydroids, polyps, 

 sponges, often attach themselves to these borrowed shells 

 (Fig. 98) ; indeed, a Chinese hermit-crab always bears an 

 anemone on its large claw, with which it plugs up the 

 aperture when obliged to retreat within its shell. One of 



