REMARKABLE TRANSFORMATION. 27 



They are enclosed in a translucent shell, consisting of 

 two valves, united by a hinge at the back, and in figure 

 much like that of a common mussel, but only one-tenth 

 of an inch in length ; within this shell the limbs are 

 capable of being completely withdrawn, and when the 

 valves are opened the animal can protrude its limbs, 

 and bring them into action. They consist of an anterior 

 pair, which are large and strong, and provided with a 

 cup-like disc or sucker, and also with hooks, and serve 

 as organs by which the creature can attach itself to 

 various objects ; behind these graspers, come six pairs 

 of limbs, orcfanized as oars, which act in concert, and 

 propel the animal along, while swimming, by a series 

 of impulsive movements, giving to the animal a leaping 

 mode of progression, as in the water-flea, (do.phiia.) 

 The tail also takes part in these movements ; it is ordi- 

 narily bent under the body, and terminates in four setee, 

 or bristle-like appendages. 



It is still more remarkable, that the young cirr- 

 hopod has large eyes set on peduncles, or footstalks, 

 (as in the lobster and other crustaceous animals,) and 

 it sees its way, and pursues by sight the almost 

 microscopic animalcules on which it preys. This con- 

 dition of existence is, however, only temporary ; after a 

 few days of Uberty a change takes place. The shells 



