234? POPULAR HISTORY OF THE AQUARIUM. 



bling its own, only somewhat larger, lay in the water. This 

 was the same animal, which had performed exuviation, and 

 extricated itself from its old shell during the night. The 

 resemblance between both forms was complete ; everything 

 was the same ; even the white limb was seen in both. 



"Another specimen kept was of smaller size; its colour 

 was green, with three white patches on the back. In the 

 course of little more than a year five exuviations took place 

 at irregular intervals ; the new shell and the animal be- 

 coming Larger each time.'' 



On the premature changes or metamorphoses Mr. Couch 

 gives the following particulars. He procured some speci- 

 mens with ova ready for shedding, transferred them to cap- 

 tivity in separate basins, and in sixteen hours found large 

 numbers of the young Zoes swimming about with all the 

 activity of life. " There could be but little doubt that these 

 young creatures were the young of the captive Crabs. In 

 order however to secure accuracy of result, one of the Crabs 

 was removed to another vessel, and supplied with filtered 

 water, that all insects might be removed ; but in about an 

 hour the same creatures were observed swimming about as 

 before. To render the matter if possible still more certain, 

 some of the ova were opened, and the embryos extracted ; 



