CRABS. 235 



but I shortly afterwards had the pleasure of witnessing, be- 

 neath the microscope, the natural bursting and escape of one 

 precisely similar in form to those found so abundantly in the 

 water. Thus then there is no doubt that these grotesque- 

 looking creatures are the young of the Carcimis mcenas ; but 

 how different they are from the adult need hardly be pointed 

 out." They are about the sixteenth of an inch long, a kind 

 of tadpole, with the body oval, surmounted by a large, long 

 spine. The pupil of the eye is large, surrounded by rays. 

 There is a kind of snout in front, and a pair of leaf-like 

 swimming appendages. The hind legs of the body are 

 natatory. The tail is long, cylindrical, divided into five 

 joints, forked at the end, and armed with stout bristles. 



These odd little creatures swim about with restless ac- 

 tivity ; but when the shell begins to harden they become 

 less active, till presently they retire to the sand at the 

 bottom of the vessel, to cast their shells and acquire a new 

 form. The second change relieves them of the tadpole ap- 

 pearance, and sets their eyes upon foot-stalks. The front 

 claws become nippers, the other claws more like those of 

 full-grown Crabs, and the tail smaller. In this stage it has 

 more of the general form of a Lobster than of its parent 

 Crab. One or two changes more, and then is produced one 



