242 



THE OCEAN WORLD. 



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, " evi- 

 dently designed by Nature to move the animal 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 polpys. Dr. Grant says, " A more 

 singular and beautiful spectacle could 

 scarcely be conceived than that of a 

 deep purple P. phosphorea with all its 

 delicate transparent polypi expanded, 

 and emitting their usual brilliant phos- 

 phorescent light, sailing through the 

 still and dark abyss, by the regular and 

 synchronous pulsations of the minute 

 fringed arms of the whole polypi;" 

 while Linn^us tells us that " the phos- 

 phorescent 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 such animals, 

 deny them the existence of this loco- 

 motive power ; " and there is little 

 doubt," says Dr. Johnston, " that these 

 authors are right, for, when placed in 

 a basin of sea-water, the Fenfiatulcs are 

 never observed to change their position ; 

 Fig. 97.-Sea-pen, Pennatuia spinosa. 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 with intercepted lines of red, which distend at one 

 place and contract at another ; they spread out the pinnae, and the 

 polyps expand their tentacula, but they never attempt to swim, or 

 perform any process of locomotioii." 



Mr. Darwin's description of a kind of Sea-pen, Virgu7dria Fata 



