74 



NATJTILUS AND AMMONITE. 



"We give below two figures of the Argonaut, one of which 

 represents him crawling at the bottom of the sea, and the 



other swimming on the surface. 



The True, or Pearly ISTautilus, {JV. Pompilius,) the origin of 

 whose specific name we have been unable to discover, is much 

 like the Argonaut in appearance and general construction; the 

 shell is externally smoother and more iridescent, it is also 

 generally somewhat thicker than the former kind, and has in- 

 ternally more chambers or divisions; its pearly lustre renders 

 it a beautiful ornament, and the large size it frequently attains 

 a very conspicuous one. Its inhabitant has several peculiarities 

 of organization, which distinguish it from the Argonauts, but 

 into these we need not enter; neither can we pause to des-. 

 cribe the other species of nautili, the shells of which, like 

 those of the Cowry and other univalves, are covered ^vith a 

 membrane which hides their beauty. This membrane or mantle 

 sometimes extends some distance beyond the edge of the shell, 

 and, being of a light and filmy appearance, may have been 

 mistaken for a sail hoisted by the creature to catch the breeze, 

 while its long arms, thrust up into the air or down into the 

 water, may have been thought to be masts or oars, so that 

 the poets are not so much to be blamed, if they say as 

 Wordsworth does. 



"Spread, tiny Xautilus, the living sail, 

 Dive at thy choice, or catch the freshening gale." 



Xearly allied to the ]S"autili are these beautiful fossil shells 

 called Ammonites, from their fancied resemblance to the horns 

 of a heathen deity or god, called Jupiter Ammon. These 

 shells, at once the wonder and pride of geologists, are found 

 in the chalk formations, and thousands of years must have 

 passed away since they were inhabited by living creatures. 



