124 Beautiful Shells. 
sometimes found on our own shores, where also may 
be obtained the Common Sepiola, S. vulgaris, 
usually about three inches long, and the Officinal 
Cuttle-fish, S. officinalis, which is about a foot in 
length ; we give below small figures of each of these 
three species, to show the difference in the shape: 
the two last, it will be observed, have, in addition 
to the eight tentacles, which give the generic 
name Octopus, signifying eight, two long side arms, 
the use of which does not appear to be very clearly 
determined. 
NAUTILUS AND AMMONITE. 
The Nautili are called testaceous cephalopods ; 
our readers know, or ought to know, the meaning 
of both these terms. Like the Cuttle-fish, they are 
sometimes called Polypi, because they have many 
arms or tentacles, the word poly, with which a great 
number of English words commence, being the 
Greek for many. An ancient writer named Aris- 
totle, after describing the naked cephalopods, says, 
_ “There are also two polypi in shells; one is called 
by some, nautilus, and by others, nauticus. It is 
like the polypus, but its shell resembles a hollow 
