472 RADIATA. 



RADIATA. 



Class I. ECHINODERMATA. — Skin coriaceous or crusta- 

 ceous ; intestinal canal distinct, and contained in an 

 abdomen ; numerous apparent vessels connected with 

 circulation aud reproduction. Marine. 



II. ACALEPHA. — Skin soft, frequently gelatinous ; 

 stomach and intestines never floating in a particular 

 cavity ; traces of circulating vessels obscure. Ma- 

 rine. 



III. ZOOPHYTA. — Mouth surrounded by a circle of 

 tentacula ; body generally compound, and assuming- 

 plant- like forms. 



IV. INFUSORIA.— Apparently destitute of a visible 



mouth, stomach, or internal vessels. ij 



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