6 
Prof. R. Owen on the Anatomy 
character. The anterior or outer side of this lip is compara¬ 
tively smooth (fig. 5) ; it is continued to the bases of the eight 
ordinary arms, and into the fold which connects together the 
contiguous sides of the bases of the third and fourth arms on 
each side, the interspace between which forms the sheath of 
the long tentacle ( d ). The outer muscular coat of the buccal 
mass (fig. 8, r) consists chiefly of a stratum of longitudinal 
fibres connected by cellular membrane to the inner coat (s), 
which consists of two subelliptical bundles of oblique fibres, 
commencing from the same mid line of the dorsal aspect of 
the buccal mass, and swelling as they proceed ventrad and 
outward to pass beneath the outer plate-layer of the under- 
(ventral) mandible to be inserted therein, as the temporal 
muscles into the coronoid processes of the vertebrate mandible, 
in the course most favourable for approximating the ventral 
(lower) to the shorter dorsal (upper) mandible. 
The inner surface of the inner lip, or labial beak-sheath, is 
produced into many deep, sharply defined radiating folds, each 
of which is indented at the base, wavy at the free margin 
(figs. 11,n, 11°). Thin bands of longitudinal muscular fibres 
pass on from the two subelliptical bundles to the inner lip, for 
its retraction. 
A labial membrane is reflected from the inner lip upon the 
outer one, at about 2 millims. from the transverse oral aper¬ 
ture ; folds of the inner lip radiate from the crenate border of 
that aperture (fig. 7, n). 
Dissection. —I proceed to note the appearances presented in 
the first steps of the dissection of my &pirula. 
On laying open the mantle along the ventral aspect the gills 
were first exposed; no rectum or anal tube appeared, at least 
no mediastinal membrane embracing a rectum in its folds, as 
in an Octopus. The gills (Pis. II. & III. fig. 1, a) are suspended 
each by a delicate frrnnum or u mesobranchia ” (/), extending 
from the base to half the length of the gill, the other half being 
free. But at the ventral interspace between the bases of the 
branchiae there is a slight prominence supporting, as in the first 
dissected specimen, the anal orifice, the oviducal orifice (PI. III. 
fig. 1, e'), and the renal outlet (fig. 3, Ic). Just within the 
border of the vent (y) opens the duct of the ink-bag (h). 
The ovary (PI. III. fig. 1, h) lies in the left hind compart¬ 
ment of the visceral chamber ; the chief folds of the oviduct 
(ib. e, PI. II. fig. 3, e) are on the right side, partially separated 
therefrom by the pellucid membrane which envelops the inner 
whorls of the shell, which membrane is also closely attached 
to the sinus surrounding the rectum. 
In the angle between the branchial hearts (PI. III. fig. 3, 
h , c ) and the intestinal fold (/) is the “ pericardial ” or 
