sive reasons for dissenting from Owen's view. On the ventral
side an extensive part of the internal surface of the muscular ring is
laminated, forming the so-called "organ of Valenciennes," peculiar to
the female and serving for the attachment of the spermatophores. We
have so far enumerated in the female nautilus ninety tentacles. Four
more remain which have a very peculiar position, and almost lead to
the suggestion that the eye itself is a modified tentacle. These
remaining tentacles are placed one above (before) and one below
(behind) each eye, and bring up the total to ninety-four (fig. 3 v,
v).

[Illustration: FIG. 6.--Male (upper) and female (lower) specimens of
_Nautilus pompilius_ as seen in the expanded condition, the observer
looking down on to the buccal cone e; one-third the natural size
linear. The drawings have been made from actual specimens by A.G.
Bourne, B. Sc., University College, London.

a, The shell.

b, The _outer_ ring-like expansion (annular lobe) of the circumoral
muscular mass of the fore-foot, carrying nineteen tentacles on each
side--posteriorly this is enlarged to form the "hood" (marked v in
fig. 1 and m in figs. 2 and 3). giving off the pair of tentacles
marked g in the present figure.

c, The right and left inner lobes of the fore-foot, each carrying
twelve tentacles in the female, in the male subdivided into p, the
"spadix" or hectocotylus on the left side, and q, the "anti-spadix,"
a group of four tentacles on the right side--it is thus seen that
the subdivided right and left inner lobes of the male correspond to
the undivided right and left inner lobes of the female.

d, The inner inferior lobe of the fore-foot, a bilateral structure
in the female carrying two groups, each of fourteen tentacles,
separated from one another by a lamellated organ n, supposed to be
olfactory in function--in the male the inner inferior lobe of the
fore-foot is very much reduced, and has the form of a paired group
of lamellae (d in the upper figure).

e, The buccal cone, rising from the centre of the three inner lobes,
and fringing the protruded calcareous beaks or jaws with a series of
minute papillae.

f, The tentacles of the outer circumoral lobe or annular lobe of the
fore-foot projecting from their sheaths.

g, The two most posterior tentacles of this series belonging to