15S 
LECTORE Xr. 
whole surface by very numerous, deeply-impress* 
edj obliquely-descending furrows ; and the keel or 
bottom is tuberculated along each side by the pro- 
jecting tips of the furrowed part of the shell. This 
shell, with its inhabiting animal, sailing along the 
surface in fine weather, has from very remote 
times attracted the admiration of mankind, and 
has been celebrated as having given the first hint 
for the practice of navigation, as if man, with all 
his powers of mind, was unable to conceive the 
possibility of swimming or sailing in a boat upon 
the water, without first receiving a hint from the 
inhabitant of a shell ! This is the species to which 
the well-known lines of Pope allude, and which 
have been so often quoted on the subject, that not- 
withstanding their real beauty, they may be consi- 
dered as almost vulgarized by frequent repetition. 
Leam of fhe little Nautilus to sail, 
" Spread the thin oar, and catch ihe rising gale.” 
As the animal which thus sails in the shell called 
the Paper Nautilus is not fastened to the shell by 
any connecting tendon, like the rest of the testa- 
ceous tribe, but has the power of leaving the shell 
at pleasure, and as its appearance is widely differ- 
