3,50 NATURALIST'S CABINET. 



Peculiar motions, &c. 



Jypes. They are very small, and generally found 

 in clear stagnant waters, during the summer 

 months, attached to the stalks of the lesser water 

 plants, where they feed on animalcules still 

 smaller than themselves. Many of the species 

 are found in groupes, sometimes formed by the 

 mere approximation of several individuals, and 

 at other times by the ramified or aggregate man- 

 ner in which they grow. Their various motions, 

 like those of the polypes, are generally exerted 

 only for the purpose of obtaining prey, the rota- 

 tory motion of their tentacula causing an eddy 

 in the water around each individual sufficient to 

 attract into its vortex such animalcules as hap- 

 pen to swim near: these the little creature seizes 

 by suddenly contracting its tentacula and inclos- 

 ing them \n the midst. The stems of several of 

 the species, into which they occasionally with- 

 draw themselves, are somewhat rigid or scaly. 

 The young are carried in oval integuments on the 

 outside of the lower part of these; and, when 

 ready to come forth, the parents aid their extru- 

 sion, where such is necessary, by writhing their 

 bodies, or striking the little vesicle. As soon as 

 the young one is liberated from its prison it fixes 

 itself, and commences the necessary operations 

 to procure its food. 



The animals of the genus vibrio are very sim- 

 ple, round, and elongated worms, nearly all invi- 

 sible to the naked eye. The species best known 



