94 



THE FLAXEN FLUSTKA. 



present about ten square inches of surface, it has 

 more than 18,000 polyps, 396,000 arms, and 

 39,600,000 cilia. Often in such observations are 

 we reminded of the words of Lucretius : 



" How many animals whose middle part 

 The sharpest eye can't see ! 

 How, then, each little member of the whole !" 



In the Flustra foliacea there are at least twice 

 as many, or 36,000 living beings, all actively 

 employed in the seizure of food, all working their 

 arms, and rapidly vibrating the cilia which cover 

 them. 



Others present stems, or leaves 

 of a horny texture, sometimes cel- 

 lular on one side only ; sometimes 

 on both. The large foliaceous flus- 

 tra, just mentioned, has cells on 

 both sides, with elevated margins ; 

 the margin of each being armed, at 

 its upper part, with two spines. The 

 extension of the cells of the flustra 

 takes place laterally, the innermost, 

 or most central, being often destitute 

 of polyps, while the external series 



POLYP OF FLUSTRA / * 



CARBACEA. of cells is tenanted. The aperture 

 of each cell of the Flustra foliacea is defended 

 by four projecting spines, which arise from the 

 calcareous margin of the cell. There are two 

 spines on each side of the aperture ; the upper two 

 being twice the length of the lower pair, and slightly 



