PENNATULJ3. 



25 



Fig. 12. Fig. 13. semblance to a quill. It 



consists of a calcareous 

 stem, the upper end of 

 which has a series of 

 branches on each side, 

 resembling the filaments 

 of a feather, and in the 

 end of each of which re- 

 sides an animal, the 

 whole being represented 

 by fig. 12. Some of the 

 polypi are seen magnified 

 in fig. 13. 



These animals are not 

 fixed like those we have described, but float along with 

 the currents of the ocean, having little or perhaps no 

 power of locomotion, though the movements of their 

 tentacula are sufficient to prevent their sinking, and to 

 enable them to rise slowly in the water. 



The Pennatulaa must be considered as a mass of dis- 

 tinct animals aggregated together to form, in many re- 

 spects, one individual. In Botany the class Syngenesia 

 presents many distinct flowers assembled together to 

 form a single compound individual, as the Thistle and 

 Dandelion, each individual being on the same receptacle, 

 and supported by the same stem. So far, therefore, as 

 aggregation is concerned, there is a strict analogy be- 

 tween a compound flower and the Pennatulae. But 

 while each individual of the Syngenesian flowers re- 

 ceives its nourishment through the same stem, the cor- 

 responding part of the compound animal, which is a 

 common stomach, receives its nourishment through hun- 

 dreds of mouths, so that here the analogy fails. 



In the Pennatulae each mouth leads into a separate 

 stomach, whence the food, after digestion, passes into 

 several channels, which proceed in different directions 

 from the cavity of each stomach, dividing into many 

 branches, and being distributed over all the surrounding 

 portions of flesh. These branches communicate with 

 similar channels proceeding from the neighboring stom- 



What is said of the stomach of the pinnatulae'? 



3 



