130 Beautiful Shells. 



The True, or Pearly Nautilus (N. PompiUus), 

 tlie origin of whose specific name we have been 

 unable to discover, is mucli 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 internally more chambers or divisions ; its 

 pearly lustre renders it a beautiful ornament, and 

 the largo size it frequently attains a very con- 



spicuous one. Its inhabitant has several pecn- 

 liarities of organization, which distinguish it from 

 the Argonauts, but into these we need not enter ; 

 neither can we pause to describe the other species 

 of Nautili, the shells of which, like those of the 

 Cowry and other univalves, are covered with a 

 membrane which hides their beauty. This mem- 

 brane 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^ 



