350 THE AQUARIAN NATURALIST. 



Thus, then, there is no doubt that these grotesque- 

 looking novelties are the young of the Carcinus 

 M&nas ; but how different they are from the adult 

 need hardly be pointed out any further than by refer- 

 ring to the figure (PL VII. fig. 4, a). When they first 

 escape, they rarely exceed half a line in length ; and 

 yet these minute creatures, in this early state of their 

 existence, are natatory and wonderfully vivacious. 

 They are continually swimming from one part of the 

 vessel to another ; and when observed free in their 

 native pools, are, if possible, even more active than 

 when in confinement. Their swimming is produced by 

 continued flexions and extensions of the tail, and by 

 repeated beating motions of their claws; this, toge- 

 ther with their grotesque-looking shape, gives them 

 a most extraordinary appearance when under exami- 

 nation. As the shell becomes more solid, they get 

 less active, and retire to the sand at the bottom of the 

 vessel to cast their shells and acquire a new form. 

 They are exceedingly delicate, and require great care 

 and attention to convey them through the first stage ; 

 for, unless the water be supplied very frequently, and 

 in great abundance, they soon die. 



The second phasis of transmutation (PL VII. fig. 4, b) 

 is equally remarkable with the first, and quite as 

 distinct from the adult animal. In the species now 

 under consideration, this second transformation is 

 marked by the disappearance of the dorsal spine. The 

 shield becomes flatter and more depressed. The eyes, 

 from being sessile, are now elevated upon footstalks. 

 The claws undergo an entire revolution; the first 

 pair becomes stouter than the others, and armed with 



