HERMIT-CRABS 



265 



well fitted to make the best of their surroundings, the body be- 

 coming modified to suit the peculiar conditions under which they 

 live. In those which inhabit shells the abdomen becomes spiral, 

 in conformity to the 

 convolutions of the 

 shell. All the ab- 

 dominal appendages 

 are more or less 

 atrophied ; the sixth 

 pair become like 

 hooks, and these 

 fasten to the colu- 

 mella of the shell, 

 keeping the crab 

 securely attached to 

 it. In the female 

 some of the abdom- 

 inal appendages 

 are hair-like and are 

 adapted to carrying 

 the eggs. The tho- 

 rax, being protected, 

 is protruded from 

 the shell at will. 



The first Pair Of feet Payurus bernhardus: ch, chela of first right leg; Z.4, 1.5, fourth 



and fifth legs ; ' t, abdominal terga ; up, last pair of appendages, 



are much larger than modified to fasten to the columella of the shell in which the hermit 



the others, and are 



provided with claws (chelae). The first right foot is usually much 

 larger than the left, and, besides the usual functions of captur- 

 ing and crushing prey, the claw, or hand, serves as an operculum 

 to close the mouth of the shell when the crab retires completely 

 within it. The small left hand is shaped to fill out the parts of 

 the opening not covered by the right one, thus making a close 

 fit. The next two pairs of feet end in simple hooks, and are 

 used for walking and dragging the crab along when he travels. 

 These crabs move about very fast, and the houses upon their 

 backs seem no encumbrance,. 



