THE FLAXEN FLUSTRA. 95 



curved upwards. When we look transversely on 

 the surface of a branch, the spines appear to be 

 arranged in very regular transverse curved rows ; 

 and when we observe the surface longitudinally, 

 they appear to be arranged in very regular longi- 

 tudinal straight lines. 



The spines are calcareous, tubular, cylindrical, 

 shut at their extremity, and obviously appear in- 

 tended to protect the expanded polyp. The two 

 pairs of spines belonging to each cell are placed 

 on the upper half of the cell, though from the 

 contiguity of the cells, the lower half of each is like- 

 wise defended by the spines of the adjacent cells, so 

 that they also serve to protect the polyps when in a 

 retracted state. No projecting spines of this kind 

 are found in the Flustra carbacea. 



According to Dr. Farre, the transparent horny 

 cell which closely embraces the body of the animal 

 is nearly unyielding in its lower two-thirds, but 

 terminates above by a flexible portion, which serves 

 to protect the upper part of the body when the 

 whole is expanded, in which state it is of the same 

 diameter as the rest of the cell ; but when the 

 animal retracts, is folded up and drawn in after it, 

 and completely closes the mouth of the cell. 



The flexible part consists of two portions : the 

 lower half being a simple continuation of the rest of 

 the cell ; the upper, consisting of a row of delicate 

 bristle- shaped processes, which are arranged parallel 

 with each other round the top of the cell, and are 



