284 MR. J. D. MACDONAI.D ON THE ANATOMY OF NAUTII.US UMBILICATUS 
/. Root of sijDliimcle. A small vessel may be seen coursing' round it 
inferiorly. 
The following parts are indistinctly visible through the mantle : — 
m. Nidarnental gland. 
n. Chamber of pericardium, lodging the base of the ventricle of the 
heart, the branchial vessels and renal follicles. 
A few globules of air are represented at the upper part of the chamber, having 
entered it by the sub-branchial openings, first described by Professor Owen. 
o. Gizzard. 
p. Ovary. 
Fig. 2. Simple dissection of the Nautilus, exposing all the more important parts of 
its anatomy, disturbed as little as possible from their natural relations. 
a. The eye slit open in the vertical direction, showing the opalescent 
retina spread over the pigmentfiry layer. The subocular hollow 
process is seen projecting from the base of the eye-pedicle, 
immediately above the cephalic cartilage f, which appears in 
section. 
h. Hood. 
c. Tentacular sheaths. 
d. Tentacula. 
e. Funnel lobe, e'. Process corresponding to^', fig. 1. 
f. Cephalic cartilage in section. 
g. Shell-muscle. 
h. Mantle, h!. Process corresponding to i, fig. 1. 
i. Buccal mass. 
j. Nervous ring of cephalic ganglia encircling the oesophagus and 
the terminal branches of the principal vessel. The long visceral 
nerves are seen passing in the interspace between the shell- 
muscles, to which a number of short radiating branches are 
distributed. 
k. Dilated portion of oesophagus forming a kind of cross. 
l. The gizzard. 
m. Sacculated portion of stomach below the gizzard, receiving the 
large biliary duct, conveying thither the secretion of the three 
principal portions into which the liver is divided, 
w, w', n” respectively, the left, right and middle mass of the liver, 
o. Biliary duct of the right division of the liver which is brought 
down from its natural position on the right side of the cross, 
the smaller extremity lying in contact with — 
'p. Peculiar glandular-looking bodies connected with the cross by 
muscular bundles and cellular tissue. 
