via 



Gorgonia, whose axe is inarticulated. The third Or- 

 der contains the Isideae, whose polypi are more ap- 

 parent, and the axe articulated. 



The fourth Class has no Order ; it is denominated 

 Carnoid Polypidoms, composed of a fleshy mass, 

 wholly animated, covered with polypi, and possess- 

 ing no central axe. 



SITUATION. 



The greater number of Polypidoms are found to 

 originate in the heart of the ocean, and in its nume- 

 rous divisions, with the exception of the Naissas and 

 the Ephydatias, which always inhabit fresh water, 

 whether stagnant or current. 



Some of the Polypidoms appear to prefer the im- 

 mediate influence of the atmospheric changes ; they 

 are seen on the rocks and on the plants which the tide 

 leaves uncovered, and sometimes in such profusion, 

 that all appear concealed under an animated mem- 

 brano-calcareous covering. These species, however, 

 at least on our shores, are neither numerous, nor at- 

 tain any considerable size. 



They almost all sufi*er from the action of the air. 

 At the period of the great equinoctial tides, the sea 

 retires from those rocks it covered for many prece- 



