228 HALF AN HOUE WITH CRUSTACEA. 



XIII. 



HALF AN HOUE WITH CEUSTACEA. 



WE have already remarked on the wonderful trans- 

 formations which a patient study of marine animals 

 has brought to light. The metamorphosis by which 

 an ugly grub is transformed, as if by magic, into a 

 gorgeous butterfly is more than equalled among 

 the jelly-fish. Not less marvellous are the changes 

 which take place in the life-history of the Crustacea. 

 The study of the latter has been much pursued in 

 this country and France during the last quarter of 

 a century. As usual, creatures which were formerly 

 considered distinct species, or genera, are now classed 

 as merely different stages in the development of the 

 same animal. More, the plan on which such well- 

 known objects as crabs and lobsters are constructed 

 is found to run more or less through the whole of 

 the Crustacea. This similarity of construction, 

 however, is not plainly visible until all the stages 

 in the development of the animal, from the egg to 

 the adult, have been noted. 



Who, for instance, would ever dream of finding a 

 second cousin to the lobster in the barnacles, which 

 encrust our rocks so as to render walking over them 

 almost impossible ? Or find, in the stalked barnacles, 

 which we see attached to the piece of drifted wreck, 



