414 



CRUSTACEA. 



that the embryo of Cancer depressus exhibited at birth a singular and 

 uncouth appearance, of which he gave a very tolerable representation*; 



Fig. 209. 



Metamorphosis of Crab. 

 Fig. 210. 



and Mr. Thompson has rendered it 

 certain that, even in the develop- 

 ment of the common Crab, so dif- 

 ferent is the outward form of the 

 newly-hatched embryo from that 

 of the adult, that the former has 

 been described as a distinct species, 

 and even grouped among the EN- 

 TOMOSTBACA, under the name of 

 Zoea pelagica. On leaving the egg, 

 the young Crab presents a curious 

 and grotesque figure (fig. 209) : its 

 body is hemispherical, and its back 

 prolonged upwards into a horn-like 

 appendage; the feet are scarcely 

 visible, with the exception of the 

 last two pairs, which are ciliated 

 like those of a Branchiopod, and 

 formed for swimming. The tail is 

 longer than the body, 

 possesses no false feet, 

 and the terminal joint is 

 crescent-shaped and co- 

 vered with long spines. 

 The eyes are very large, 

 and a long beak projects 

 from the lower surface 

 of the head. 



(1064.) In a more 

 advanced stage of growth 

 the creature assumes a 

 totally different shape 

 (fig. 210), under which 

 form it has been known 

 to naturalists by the 

 name of Megalopa. The 

 eyes become peduncu- 

 lated, the cephalothorax 

 rounded, the tail flat and 

 provided with false feet, 

 and the chelae and am- 

 bulatory extremities well developed. 



* Sulla Generazione dci Pesci e del Granchi. 4to. Naples, 1787. 



Metamorphosis of Crab. 



