OF THE UNITED STATES 



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common edible species, and the one best known in ancient times 

 to the Romans. The list of crabs now known to science is a 

 loan one indeed, and they are found in suitable localities in 

 nearly every part of the world. Most of us are familiar with the 

 little " oyster crab " found in those bivalves. The adull females 

 of this diminutive species live within the gill cavities of oysters, 

 while the males usually swim about at large. They have often 

 been described by naturalists as different species, and there has 

 been excuse for this, as the sexes are so essentially different in 

 appearance. Mussels harbor another variety of these tiny 

 crustaceans. The question as to how these little creatures orig- 



Fig. 5. The Violet Land Ckab. 



Drawn by the Author. 



inally came to take up their abode within the shells of living 

 bivalves has not been settled. 



Englishmen call these oyster-crabs " pea-crabs," and they 

 stand among the smallest representatives of the group, the big- 

 gest form known being the crab-giants of Japan, which are 

 considered a delicacy by the Japanese. A specimen of one of 

 these has pincers each five feet long. Like our marine spider- 

 crabs, its triangular body is not large in proportion. 



In the islands of the Indian Ocean they have the " robber 

 crabs" — species that approach the lobsters in their structure. 

 But instead of living in the water, they burrow at the feet of the 



