148 



ANIMAL KINGDOM. 



stomach for eating and digestion, and hence they are widely 

 diverse from plants. 



The figs. 147 to 156 represent examples of Eadiates: 147, an 

 Actinia, or Polyp; 148, 149, living corals, the animals of which are 

 polyps ; 150, a Medusa, or Acaleph, — also called Jelly-fish, — showing 

 well the internal as well as external radiate structure, as the animal 

 is nearly transparent; 151, 152, polyp-like species of the class of 

 Acalephs ; 153, an Echinus, or Sea-urchin, — but not perfect, as the 

 spines which cover the shell and give origin to the name Echinus 

 are removed from half its surface to show the shell ; 154, a Star-fish; 

 155, 156, Crinoids, — animals like an inverted Star-fish or Echinus, 



Figs. 147-156. 



Radiates, figs. 147-156. 1. Polyps: Fig. 147, an Actinia; 148, a coral, Dendrophyllia ; 149, a 

 coral of the genus Gorgonia. 2. Acalephs : 150, a Medusa, genus Tiaropsis ; 151, Hydra 

 (X8); 152, Syncoryna. 3. Echinoderms : 153, Echinus, the spines removed from half 

 the surface (X %); 154, Star-fish, Palaeaster Niagarensis; 155,Crmoid,Encrinusliliiformis; 

 156, Crinoid, of the family of Cystids, Callocystites Jewettii. 



standing on a stem or pedicel, like a flower. Fig. 157 is the shell 

 of another Sea-urchin ; and fig. 158, another Crinoid. Figs. 523 

 to 535 are additional examples of Eadiates. 



The radiate feature exists not only in the external form, but also 

 in the interior structure. The mouth, when furnished with cal- 

 careous jaws or mandibles, has a circle of five of them ; and the 

 nervous system, when distinct, is circular in arrangement. 



II. Mollusks. — The structure essentially (1) a soft, fleshy bag, 



