SYSTEMATIC 

 ARBANGEMENT OF POLYPS. 



CLASS II. 

 POLYPI. 



ANIMALS contractile, having an intestinal cavity, with distinct 

 terminal mouth, surrounded by tentacles or radiating lobes, seldom 

 free, oftener affixed, aquatic; usually secreting a hard calcareous 

 or horny body (polypary), and adhering to it. 



Propagation is by eggs, gems, stolons. Usually compound ani- 

 mals are formed of many individuals cohering. 



SECTION I. Anthozoa EHRENB. 



Aperture of the nutrient canal single. Tentacles contractile, 

 mostly without vibratile cilia. 



ORDER I. Hydriformia. 



Tentacles of variable number. Nutrient canal excavated in the 

 parenchyme of the body, not surrounded by an abdominal cavity. 



Family I. Hydrina. Naked, free, spontaneously affixed, with 

 deciduous progeny. 



Hydra L. Body cylindrical, narrowed into a pedicle, simple or 

 ramose from the progeny not having been detached. Mouth 

 crowned with tentacles, round, contractile, in a single whorl. 



Armed-Polyp: Sp. Hydra viridis, TBEMB. PL I. fig.; ROES. Ins. in. 

 Polyp. Tab. 88, 89. This green species was the first which TREMBLEY 

 found ; it is rarer and smaller than the others. H. Grisea, TBEMB. 

 PL i. fig. 2 ; H. fusca, TBEMB. PL i. fig. 3, 4, polype a longs bras, 



