88 THE ANATOMY OF THE NAUTILUS POMPILIUS 
Mr. Macdonald, in a valuable paper on the anatomy of Nautilus 
umbiicatus, published in the Philosophical Transactions for 1855, 
thus describes the follicular appendages of the branchial arteries :-— 
“These follicles are subcylindrical in form, somewhat dilated at 
the free extremity, to which is appended a folded and funnel-shaped 
process of membrane, which expands rather suddenly, presenting a 
jagged and irregular border. They open by a smooth and oval or 
slit-like orifice into the afferent pulmonary vessels, on each of which, 
as Professor Owen has observed, they are disposed in three clusters. 
The outer membrane is smooth and glassy, homogeneous in structure 
A | 
Fic. 2.—NMautilus pompilius. Natural size. 
The pallio-visceral ligament scen from below: torn on the right side to show the rectum and 
oviduct ; cut through on the left side along the dotted line close to @”’ in the preceding 
figure. 
vw. Anus. 6. Oviducal aperture. c. Heart. d@. Left branchial veins. ¢. Right branchial 
veins. # Oviduct cut through. g. Ovary. 4%. Rectum. 2 Mantle. £242, Pallio- 
visceral ligament; 4’. its torn portion, The oval ‘‘ aperture for the siphonal artery’ is 
seen to the left of c’, and the right-hand style in Fig. 1 passes through it. 
and sprinkled over with minute rounded and transparent bodies, 
probably the nuclei of cells. Beneath this layer, flat bundles of 
fibres, apparently muscular, are traceable here and there, principally 
disposed in a longitudinal direction, and sometimes branched. The 
lining membrane consists of a loose epithelial pavement in many 
respects similar to that of the uriniferous tubules of the higher 
animals, the cells containing, besides the nuclei, numerous minute 
oil-globules, or a substance much resembling concrete fatty matter. 
This membrane is thrown up into an infinite number of papilla and 
corrugations, so as to augment the extent of surface considerably. 
