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. 



