52 



CRUSTACEA. 



third, and fourth have limbs on the left side only Co- 

 holding the eggs during the period of oviferation ; tlu 

 fifth is extremely small, and shows on the left side jus 

 above/6 in Fig. 23. /6 are the only complete pail 

 and they are modified into claspers for holding tin 



Fig. 33. 



Eupagurus folicaris (after Morse). 



The hermit-crab, as it appears when partly protruded from the shell in the 

 act of walking. 



animal is a shell, rg is a hard ridge, which, like the 

 projection on the opposite side, is useful in holding 

 against the columella of the shell. The crab has 

 adopted the curious habit of depending upon the shells 

 of sea-snails for protection, and the softness of the 

 abdomen is due to the effect of the artificial covering 

 of this part, as may be seen by comparison with the 

 less protected abdomen of Lithodes. 



Usually, empty shells arc chosen, though sometimes 



