CRABS AND LOBSTERS. 133 



from the segments have some right to be called, twenty pairs 

 in number, we find them successively devoted to seeing, feel- 

 ing, and otherwise perceiving, feeding, and presumably tasting, 

 grasping and striking, walking and digging, swimming and 

 leaping. But although the order in which they act may thus 

 be generally stated, there is not unfrequently a transfer of 

 function from one part of the line to another. The feelers may 

 be employed to assist in swimming or climbing or clasping. 

 The mouth-organs of one group are the grasping weapons of 

 another. The walking legs of one set are elsewhere adapted 

 for swimming. There are also other functions conjugal or 

 maternal, in which the swimming legs or the walking legs may 

 take part, while the breathing apparatus, simple or compli- 

 cated, may be connected with the mouth-organs or limbs of 

 the trunk or both, or else with the swimming organs of the 

 tail-part, commonly called the pleon." (Stebbings*) 



What may be called the personal or life-history of the Great 

 Crab is a scientific romance. Once upon a time there was a 

 grotesque sea monster as big as the head of a good-sized pin 

 *hat resembled in a small way a German soldier's spiked 

 helmet, with a couple of huge eyes in front of it, a long jointed 

 tail behind it, and a few bristles around its edge. This creature 

 naturalists recognised as a distinct species, to which they gave 

 the name Zoea taunts. It was first taken from the sea by a 

 Dutch naturalist, one Martin Slabber, in the year 1768, but his 

 account was not published until ten years later, whereupon 

 Bosc created a new genus to receive the little oddity. Then 

 there was another sea creature, not much larger, but having a 

 distant resemblance to a lobster, and for this form Leach 

 founded his genus Megalopa. Now it chanced that an Irish 

 naturalist, Mr. J. Vaughan Thompson, nearly fifty years later, 

 thought he would like to verify Slabber's observations, and he 

 searched for the supposed-rare Zoea^ and found it in profusion. 

 He watched its progress in life, and lo ! he beheld Zoea cast 



* History of Recent Crustacea : International Scientific Series, 1893. 



