8 
Prof. R. Owen on the Anatomy 
The liver occupies a special peritoneal sac reflected from the 
dorsal aspect of the lobes upon the ventral curvature of the 
last chambers of the shell. 
On dissecting aside from the median line the thick layer 
(PI. III. fig. 2, k) of the longitudinal muscular bands (re- 
tractores capitis) which pass backward from the ventral side 
of the skull, above and behind the base of the funnel (ib. i ), 
a cavity was laid open from which escaped much fine granular 
and oily globular matter: Iliad tapped, in fact, the hepatic 
follicles (l f ). 
The muscular parietes of the funnel (PI. III. figs. 1, 2, i) 
are 1 mi Him. thick at its base, becoming gradually thinner to 
the apex. The aperture at this part is half a millim. in 
diameter, and is defended by a flat semicircular valve {}), 
attached by its base to the inner surface of the dorsal aspect 
of the infundibular wall. 
The u retractores infundibuli ” (PI. I. fig. 4, t ; PI. II. fig. 
2, /, fig. 1,./’), arising from the aponeurotic sheath (ib. y) of 
the last shell-chamber (ib. w), advance, inclining, at first, ven- 
trad to the sides of the base of the funnel, pass under the 
pallial valve (fig. 3, h) and blend peripherally with its inner 
surface; they next, by a free margin, blend centrally with 
the mass of the 11 retractores capitis ” (PI. II. fig. 2,/), closing 
the communication between the cavity of the mantle and the 
cavity of the funnel at that part. 
The retractores infundibuli originate partly from the inner 
surface of the peripheral wall of the last shell-chamber, partly 
from an aponeurosis (ib. y) which spreads over the wall of that 
and preceding chambers, beneath the part of the peritoneum 
which is reflected therefrom to line the mantle. 
One thin fascicule (PI. II. fig. 2 ,f) attached to the pallial 
ganglion (d) passes distad and ventrad to the mantle: a 
broader aponeurotic sheath is continued from the muscles 
over the involute whorls of the shell (PI. II. fig. 2, w } y). 
The valvular pallial fold (PI. I. fig. 4, li ; PI. III. fig. 1, h) 
is muscular, and is continued partly from the base of the 
funnel, mainly from the muscular walls of the head. 
The u retractores capitis ” (PI. II. figs. 2, 3, /'), attached to 
the cranial cartilage, converge as they pass backward, become 
connected with the u retractores infundibuli,” and finally 
spread upon the walls of the last chamber of the shell (ib. w), 
which serves as a fixed point for the origins of those muscles. 
A delicate but firm membrane (PI. II. fig. 4, u) is reflected 
from such muscular sheath of the shell-mouth upon and over 
the margin of the outer shell-chamber into its cavity, and 
upon the hemispheric mass (ib. z ) occupying that chamber, and 
attached to the hind ends of the lobes of the liver (ib. I, l'). 
The muscular fibres of the shrunken fin-like appendages 
