12 GENERAL SURVEY OF THE ANIMAL KINGDOM. 



ectoderm or epiblast, internal endoderm or hypoblast lining the gut, 

 and a median mesoderm or mesoblast lining the body cavity). In the 

 next two classes (Ccelentera and Sponges) the conditions are different, 

 as may be expressed in the following table : 



Ccelentera. This series includes jelly-fishes, sea-anemones, 

 corals, zoophytes, and the like, most of which are equipped 



FIG. 1 6. Sea-anemones on back of hermit-crab. 

 After Andres. 



with stinging cells, by means of which they paralyse their 

 prey. All but a few are marine. The body may be a 

 tubular polyp, or a more or less bell-like " medusoid," and 



