ecum. In all but _Nautilus_
the caecum lies near the stomach, and may be very capacious--much
larger than the stomach in _Loligo vulgaris_--or elongated into a
spiral coil. The simple U-shaped flexure of the alimentary tract, as
seen in fig. 10, is the only important one which it exhibits in the
Cephalopoda. The acini of the large liver of _Nautilus_ are compacted
into a solid reddish-brown mass by a firm membrane, as also is the
case in the Dibranchiata. The liver has four paired lobes in
_Nautilus_, which open by two bile-ducts into the alimentary canal at
the commencement of the intestine. The bile-ducts unite before
entering the intestine. In Dibranchiata the two large lobes of the
liver are placed antero-dorsally (beneath the shell in Decapoda), and
the bile-ducts open into the caecum. Upon the bile-ducts in
Dibranchiata are developed yellowish glandular diverticula, which are
known as "pancreas," though neither physiologically nor
morphologically is there any ground for considering either the
so-called liver or the so-called pancreas as strictly equivalent to
the glands so denominated in the Vertebrata. In _Nautilus_ the
equivalents of the pancreatic diverticula of the Dibranchs can be
traced upon the relatively shorter bile-ducts.

[Illustration: FIG. 9.--Lingual dentition of Cephalopoda. A, A single
row of lingual teeth of _Nautilus pompilius_ (after Keferstein). B,
Two rows of lingual teeth of _Sepia officinalis_ (after Troschel). C,
Lingual teeth of _Eledone cirrhosa_ (after Loven).]

[Illustration: FIG. 10.--Diagram representing a vertical approximately
median antero-posterior section of _Nautilus pompilius_ (from a
drawing by A.G. Bourne). The parts which are quite black are the cut
muscular surfaces of the foot and buccal mass.

a, The shell.

b, The nuchal plate, identical with the nuchal cartilage of _Sepia_
(see fig. 2, b).

c, The integument covering the visceral hump.

d, The mantle flap or skirt in the dorsal region where it rests
against the coil of the shell.

e, The inferior margin of the mantle-skirt resting on the lip of the
shell represented by the dotted line.

f, The pallial chamber with two of the four gills.

g, The vertically cut median portion of the mid-foot (siphon).

h, The capito-pedal cartilage (see fig. 8).

i, The valve of the siphon.

l, The siphuncular pedicle (