POLYPI. 



165 



wusica, as shown in Fig. 61. In Fig. 62, a 

 portion of the tubes is seen 

 highly magnified, and laid 

 open, to show the polypes in 

 their interior. At other times 

 the tubes are joined together 

 endwise, like the branches of 

 a tree, leaving lateral aper- 

 tures for the protrusion of the 

 tentacula of each separate 



polype : this is the case in the Sertularia. 



(Fig. 60.) 



61 



In some species the horny base is fashioned 

 into a number of cells, each of which serves for 

 the protection of its respective polype. These 

 cells are generally placed at the extremity of 

 the branches, presenting the greatest similitude 

 to flowers. The Flustra (Fig. 63) is composed 

 of minute and almost microscopic cells, spread 

 over a flat membraneous substance, resembling, 

 in the flexibility of its texture, and its mode of 

 subdivision, the leaves of plants. These cells are 

 arranged in rows, with great regularity, like those 



