268 SEA FABLES EXPLAINED. 



Hence took the hint, hence formed th' imperfect draught, 



And ship-like fish the future seaman taught. 



Then mortals tried the shelving hull to slope, 



To raise the mast, and twist the stronger rope, 



To fix the yards, let fly the crowded sails, 



Sweep through the curling waves, and court auspicious gales." 



Pope, too, in his ' Essay on Man ' (Ep. 3), adopted the 

 idea in his exhortation 



" Learn of the little Nautilus to sail, 

 Spread the thin oar, and catch the driving gale." 



Poetry, like the wizard's spell, can make 



"A nutshell seem a gilded barge, 

 A sheeling seem a palace large," 



but the equally enchanting wand of science is able by a 

 touch to dispel the illusion, and cause the object to appear 

 in its true proportions. So with the fiction of the " Paper 

 Sailor." 



I have elsewhere described the affinities of the Nautili 

 and their place in nature, therefore it will only be necessary 

 for me here to allude to these very briefly, to explain the 

 great and essential difference that exists between the two 

 kinds of Nautilus which are popularly regarded as being 

 one and the same animal. 



The Pearly Nautilus (Nautilus pompilius] and the 

 Argonaut, which from having a fragile shell of somewhat 

 similar external form is called the Paper Nautilus, both 

 belong to that great primary group of animals known as 

 the Mollusca, and to the class of it called the Cephalopoda, 

 from their having their head in the middle of that which is 

 the foot in other mollusks. In the Cephalopoda the foot is 

 split or divided into eight segments in some families, and 

 in others into ten segments, which radiate from the central 

 head, like so many rays. These rays are not only used as 



