CORALLINES. 



141 



the middle ; pinnae close ; polyp cilia uniserial, tubular, with spinous 

 apertures. (Sibbald.) 



Bohadsch says the Pennatulx swim by means of their pinnas, 

 which they use as fishes do their fins. Ellis says, " It is an animal 

 that swims about in the sea, many of them having a muscular motion 

 as they swim along ;" these motions being effected, as he tells us in 

 another place, by means of the pinnules or feather-like fins, " evidently 

 designed by Nature to move the ani- 

 mal backward or forward in the sea." 

 Cuvier tells us they have the power of 

 moving by the contraction of the fleshy 

 part of the polypidom, and also by the 

 combined action of its polyps. Dr. 

 Grant says, " A more singular and beau- 

 tiful spectacle could scarcely be con- 

 ceived than that of a deep purple P. 

 plwspliorea with all its delicate trans- 

 parent polypi expanded, and emitting 

 their usual brilliant phosphorescent 

 light, sailing through the still and 

 dark abyss, by the regular and syn- 

 chronous pulsations of the minute 

 fringed arms of the whole polypi ;" 

 while Linnaeus tells us that " the 

 phosphorescent sea-pens which cover 

 the bottom of the ocean cast so strong 

 a light, that it is easy to count the 

 fishes and worms of various kinds 

 which sport among them." 



Lamarck, Schweigger, and other 

 naturalists, however, reasoning from 

 what is known of other compound animals, deny the existence of this 

 locomotive power in these zoophytes ; " and there is little doubt," says 

 Dr. Johnston, " that these authors are right, for, when placed in a 

 basin of sea water, the Pennatulee are never observed to change their 

 position ; they remain in the same spot, and lie with the same side up 

 or down, just as they have been placed. They inflate the body until 

 it becomes to a considerable degree transparent, and only streaked 



Fig. 61, Sea-pen, Pennatula spinosa. 

 (Edes.) 



