ANIMAL KINGDOM. 219 



it to the entrance of the intestinal canal. Still the method 

 in which this prey is seized is more analogous to the man- 

 ner in which insects are entrapped by various plants, than 

 to that peculiar will which we perceive in the more per- 

 fect animals when hungry. An object must irritate the 

 tentacula of the Polype by contact before these will con- 

 vey it to the mouth. The alimentary canal is indeed the 

 principal characteristic of the Polypes ; for, except in this 

 respect, the structure of some of them can hardly be said 

 to be more complicated than that of the Infusoria. The 

 gelatinous pulpy body of the Polype is now however 

 protected by an inorganic sheath, and the animal is in ge- 

 neral composite. 



By a Composite Animal we are to understand a con- 

 glomeration of the same species, adhering the one to the 

 other, either by lateral appendages or by their posterior 

 extremities, and which communicating together by such 

 means, assimilate in common the nutriment which one alone 

 has swallowed. It is a collection of animals which parti- 

 cipate in a common life, while each enjoys an independent 

 vitality for every part of its body. We have already seen 

 instances of this compound organization among the Polypes 

 nus of Cuvier, as in the genera Vorticella and Cristatella; 

 but the difference between these and the compound sheath- 

 ed Polypes seems to be, that each of the latter is insulated 

 in front, and confined in a little cell formed of the horny 

 crustaceous or stony matter which transudes from its sur- 

 face, while by its posterior extremity, like the Polypes nus, 

 it is connected ^,vith its fellows. 



The Polypi vaginati are very numerous in nature, and 

 constitute an ample and interesting field, in which a na- 

 turalist may acquire great honour. They appear to contain 



