216 



EVENINGS AT THE MICROSCOPE 



partially bent under the body, but is more commonly ex- 

 tended. This form is as natatory as the first. They are 

 frequently found congregating around floating sea-weed, 

 the buoys and strings of the crab-pot marks, and other 

 floating substances, both near the shore and in deep water. 

 Their general form somewhat resembles a Q-alaihea." 1 

 Thus under Mr. Couch's eye the Zoea had changed to 



SECOND STAGE OF SHORE-CRAB. 



a Megalopa; and this latter became after a short time a 

 Crab, in which were all the characters that belong to the 

 order to which the parent belongs; but not those of the 

 genus, nor even of the family. Its form bore a close re- 

 semblance to that of the Sargasso Crabs (Grrapsidce)] for 

 the shield, instead of being large and arched in front, and 

 narrowed behind, was nearly square, while the front was 



* "Rep. Cornw. Polyt. Soc.," 1843. 



