SWIMMING CRAB. 



175 



treated of as a separate creature from the crab, 

 4 for it bears about the same resemblance to the 

 crab that a caterpillar bears to a butterfly, or a 

 wire-worm to a beetle. The long tail of the Zoea 

 formed one of the distinctive points that sepa- 

 rated it from the crabs j and yet, if a crab is laid 

 on its back, a tail is seen to be tucked up under 

 its body, in a position something like that assumed 

 by the tail of an alarmed dog. 



Many species of crabs may be found on the sea- 

 shore; that is, if they are sought in the proper 

 localities. The two species already mentioned are 

 totally incapable of swimming. They can crawl 

 upon the shore, half bury themselves in the sand, 

 or .push their way among the algse with much 

 rapidity ; but if they are thrown into deep water, 

 they sink helplessly to the bottom, spreading 

 about their limbs in the vain search after some 

 object which they can grasp. There are, how- 

 ever, several species of crabs found on the British 

 shores, which are good swimmers, one of which 

 is given on plate m, fig. 4. This is the Velvet 

 Swimming Grab, or the Velvet Fiddler, as it is 

 sometimes called. If the figure of this animal be 

 compared with that of the common crab, on p. 173, 

 the reader will observe that there is a consider- 

 able difference between the two creatures; one of 



