MOLLTISCA. 
14 
extremity of the shell — this column is termed the siphon. The turns 
of the spire do not come into contact. 
But a single species, Nautilus spirula, L. ; List., 550, 2, is 
known. The 
Nautilus, projaer/y so called. 
Has a shell which differs from the Spirula in the sudden crossing 
of the laminse, and in the last turns of the spire, which not only touch 
the preceding ones but envelope them. The siphon occupies the 
centre of each septum. 
N.pompUius, L. ; List. 551, the most common .species ; it is 
very large, formed internally of a beautiful mother-of-pearl, and 
covered externally Avith a white crust varied with fawn-coloured 
bands or streaks(a). 
I’lie animal, according to Rumphius, is partly contained within 
the last cell, has the sac, eyes, parrot-beak, and funnel of the 
other Cephalopoda ; but its mouth, instead of having their large 
feet and arms, is surrounded by several circles of numerous 
small tentacula without cups. A ligament arising from the back 
traverses the whole siphon and fastens it there*. It is also 
probable that the epidermis is extended over the outside of the 
shell, though we may presume it is very thin over the parts that 
are coloured. 
Individuals are sometimes found, — Naut. powpilius, Gmel.; 
List., 552; Ammonie, Month, 74, in which the last whorl does 
not envelope and conceal the others, but where all of them, 
though in contact, are exposed, a circumstance which approxi- 
mates them to the Ammonites ; they so closely resemble the 
common species, hov’ever, in all the rest of the shell, that it is 
scarcely possible to believe them to be any thing more than a 
variety of it. 
Fossil Nautili are found of a large or moderate size, and 
much more various, as to form, than those now taken in the 
oceanf. 
Chambered shells are also found among fossils, furnished with 
simple septa and a siphon, the body of which, at first arcuated, or 
even spirally convoluted, remains straight in the more recent parts ; 
they are the Lituus of Breyn, in which the whorls are sometimes 
contiguous^, and sometimes distinct — the Hortoles of Montfort. 
* The figure of Rumphius is absolutely unintelligible, and it is somewhat asto- 
nishing, that, of the many naturalists who have visited the Indian Ocean, not one has 
ever examined or collected this curious animal, which belongs to so common a shell. 
-f Large species, with a sinple siphon: the Angulite, Mont., f. 1, 6; — the 
Aganide, Id., 50 ; — the Cantrope, Id., 46. 
X Nautilus lituus, Gm. ; — Naut. semilituus, Plane., I, x. 
(a) See a very beautiful ilhistration of a specimen of Nautilus, by Richard 
Owen, Esq. — ^E ng. Ed. 
