h the sides
of the funnel. In _Sepia_ and other Decapods (not in Octopods) a
closely similar plate exists in an exactly corresponding position (see
b in figs. 10, 26). In _Sepia_ a cartilaginous development occurs here
immediately below the integument forming the so-called "nuchal plate,"
drawn in fig. 8, D. The morphological significance of this nuchal
lamella, as seen both in _Nautilus_ and in _Sepia_, is not obvious.
Cartilage having the structure shown in fig. 7 occurs in various
regions of the body of Cephalopoda. In all Glossophorous Mollusca the
lingual apparatus is supported by internal skeletal pieces, having the
character of cartilage; but in the Cephalopoda such cartilage has a
wider range.

In _Nautilus_ a large H-shaped piece of cartilage is found, forming
the axis of the funnel (fig. 8, A, B). Its hinder part extends up into
the head and supports the peri-oesophageal nerve-mass (a), whilst its
two anterior rami extend into the tongue-like siphon. In _Sepia_, and
Dibranchs generally, the cartilage takes a different form, as shown in
fig. 8, C. The processes of this cartilage cannot be identified in any
way with those of the capito-pedal cartilage of _Nautilus_. The lower
larger portion of this cartilage in _Sepia_ is called the cephalic
cartilage, and forms a complete ring round the oesophagus; it
completely invests also the ganglionic nerve-collar, so that all the
nerves from the latter have to pass through foramina in the cartilage.
The outer angles of this cartilage spread out on each side so as to
form a cup-like receptacle for the eyes. The two processes springing
right and left from this large cartilage in the median line (fig. 8,
C) are the "pre-orbital cartilages"; in front of these, again, there
is seen a piece like an inverted T, which forms a support to the base
of the "arms" of the fore-foot, and is the "basi-brachial" cartilage.
The Decapod Dibranchs have, further, the "nuchal cartilage" already
mentioned, and in _Sepia_, a thin plate-like "sub-ostracal" or
(so-called) dorsal cartilage, the anterior end of which rests on and
fits into the concave nuchal cartilage. In Octopoda there is no nuchal
cartilage, but two band-like "dorsal cartilages." In Decapods there
are also two cartilaginous sockets on the sides of the
funnel--"siphon-hinge cartilages"--into which fleshy knobs of the
mantle-skirt are loosely fitted. In _Sepia_,