180 CRUSTACEANS. 



the ueighbouring genera, to which it may not be inconveniently attached 

 as an appendage. 



The shell, when nearly full grown, may be circumscribed by an ellipse 

 of two inches by an inch and three quarters, the feet expanding seven 

 inches. Nearly the same proportions prevail universally in those of all 

 dimensions. The eyes and antenute much resemble those of the preceding 

 Crabs. The former, sustained on stout peduncles, fold laterally from the 

 root into cavities on the edge of the shell, the two forked antenna?, within 

 two of setaceous form, are in constant motion. The exterior edge of the 

 shell, Ijehind each eye, is serrated by five teeth, and three others are on the 

 marginal portion in front between the eyes. A large spine rises from the 

 second joint of each claw, besides which are some smaller spines. The 

 extremities of the posterior limbs are of an oval form, the external ar- 

 ticulation as if divided also by one of flatter shape interposed, — whereby 

 the animal is enal^led to sprmg vigorously through the water, and is 

 thence denominated the Flyimj Crab by fishermen. 



The flattened portion is finely and completely fringed. 

 The shell of this animal is stained by various colours, red, blue, and 

 white, modified on the back in numerous shades, forms, and intensities. 

 In fine and beautiful constrast, the under surface is universally of pure and 

 delicate white. Two crescents of minute white specks, much resembling 

 the form and appearance of a pair of spectacles, are always seated on the 

 upper surface of fine specimens. The animal is seldom seen of uniform 

 colour ; it is variegated. The symmetry of the whole shell, and its 

 various parts, are admirable. — Plate XLII. fig. 1. 



This is a lively creature ; it spi'ings suddenly on its prey, though not 

 so fiercely as the Cancer mcenas. A great quantity of food is devoured 

 at once, and the animal is ever ready to feed, crouching down in quies- 

 cence after a voracious repast, wherein all other animal substances are 

 acceptable. 



Perhaps, from its conformation, the Porfimus lividus may resort to 

 deeper water. It remains always completely immersed in confhiement, 

 never testifying the desire betrayed by other specimens, of quitting its 

 element occasionally, or indifference at continuing a short time dry. 



