1 88 INTRODUCTION TO ZOOLOGY. 



poets would not fail to celebrate its nautical capabilities.* 

 Thus, Pope bid us 



" Learn of the little Nautilus to sail, 

 Spread the thin oar and catch the driving gale." 



And Montgomery, in his " Pelican Island," gives a picture so 

 exquisitely finished, that even the naturalist can scarcely 

 bring himself to wish that it were different : 



" Light as a flake of foam upon the wind, 

 Keel upward from the deep emerged a shell, 

 Shaped like the moon ere half her horn is lili'd ; 

 Fraught with young life, it righted as it rose, 

 And moved at will along the yielding water. 

 The native pilot of this little bark 

 Put out a tier of oars on either side, 

 Spread to the wafting breeze a twofold sail, 

 And mounted up and glided down the billow 

 In happy freedom, pleased to feel the air, 

 And wander in the luxury of light." 



It is now ascertained that the Nautilus never moves in the 

 manner here described. The account, though so universally 

 accredited, is altogether fabulous. It moves backwards through 

 the water by the action of its arms, like other Cuttle-fish. 

 It can creep along the bottom, and, like many other Mollusks, 

 it can rise to the surface; but there, the arms are never em- 

 ployed as oars. Nor are those which have the broad expanded 

 membranous disc ever used as sails ; their true function, as 

 ascertained by M. Eang, and confirmed by the experiments 

 of Madame Power, is the secretion of the substance of the 

 shell. They are stretched tensely over its surface, and, when 

 accidental injuries arise, they deposit for its repair the needful 

 quantity of shelly matter. To do this, and to supply what is 

 wanted for the enlargement of the shell with the growth of 

 the animal, is their appointed duty ; one similar to that of the 

 mantle of the bivalve shells. 



* Byron's well-known description is too beautiful to be omitted: 

 "The tender Nautilus who steers his prow, 

 The sea-born sailor of his shell canoe, 

 The ocean Mab, the fairy of the sea, 

 Seems far less fragile, and, alas ! more free. 

 He, when the lightning-wing'd tornados sweep 

 The surge, is safe his port is in the deep 

 And triumphs o'er the armadas of mankind, 

 Which shake the world, yet crumble in the wind." 



THE ISLAND. 



