CLASSIFICATION AND CREATION. 49 
tion shows in these animals, as distinctly as in all 
_the rest, the radiating structure typical of the 
whole branch. In these three classes we have 
no difference of plan, nor even any modification 
of the same plan, —for either one of them ex- 
presses it as clearly as any other, — but simply 
three different ways of executing one and the 
same structural idea. 
To those already familiar with these animals 
some technical details showing the absolute iden- 
tity of structural plan in these three classes of 
Radiates may not be uninteresting. 
Let us therefore return to the Polyps, and look 
at the Sea-Anemone in a new aspect. Sup- 
pose the inner sac to be turned out; it will 
then present the appearance of a bottle-shaped 
body, with a row of hollow projections around 
the base of the neck; the neck itself being the 
stomach turned outward, so that its inner surface 
becomes its outer surface. If we now compare 
this with the Jelly-Fish, placing both in the same 
attitude, with the mouth either downward or 
upward, it becomes apparent that the so-called 
arms surrounding the mouth of the Jelly-Fish 
correspond exactly to the neck .of our bottle- 
shaped animal, with the sole difference that it 
es split into lobes in the Jelly-Fish, instead of 
remaining tubular as in the Polyp. There are, 
however, many Jelly-Fishes in which it is strictly 
3 D 
