POLYPES. 167 



as it is called, consisting often of innumerable 

 cells, each containing a separate individual with 

 its mouth and tentacles, united to the general 

 body at its other extremity, and each with an 

 external aperture, by which they are protruded, 

 and expand like a flower. 



3. In the Coral and affinities, 1 it forms an 

 internal calcareous axis, which it envelopes as 

 the bark does the tree : it is fixed by its base 

 like the preceding tribe ; and from this crust, 

 or bark, the tentaculiferous mouths of the 

 polypes emerge. In some the axis appears 

 articulated. 



N.B. In these two last the base by which the 

 compound animal is fixed to rocks, or other 

 substances, expands like the base or root of a 

 tree ; and by their ramifications these polypes, 

 whether the polypary is external or internal, 

 resemble its branching stem. 



4. The Sponges* and Alcyons 3 have been 

 generally arranged with the last Order, but, from 

 M. Savigny's observations, it appears that cer- 

 tain of these animals have neither stomach, 

 mouth, nor tentacles, the animal life of which he 

 thinks might be disputed ; but Mr. Bell has 

 discovered that they alternately imbibe and 

 expel that fluid, which seems to prove their 

 animal nature. Perhaps they ought to be con- 



1 Corticifera, Lair. 2 Spongia. 3 Alcyonium. 



