band with
the surface of the apex of the ovary; but on the right, for the greater
part of its extent, receives a process of the pallio-visceral ligament.
Between the ovario-cardiac ligament and this process lies the small oval
aperture already described by Professor Owen, which gives passage to the
siphonal artery. It constitutes the middle aperture of communication
between the two divisions of the fifth chamber.

The left-hand end of the ligament is inserted into the upper wall of the
dilated end of the vena cava; but between this point and the heart it
has a free arcuated edge, as on the right side.

Thus there are in reality three apertures of communication between the
two divisions of the fifth chamber, the middle, by far the smallest,
being alone hitherto known.

A delicate membranous band passes from the whole length of the middle
line of the rectum to the heart and to the ovary.

The singular "pyriform appendage" of the heart lies in the left process
of the ligament, its anterior edge nearly following the arcuated contour
of that process.

The siphuncular process of the mantle was broken in my specimen; but
its aperture appeared to communicate quite freely with the posterior
division of the fifth chamber.

Four sets of brownish, glandular-looking bodies depend into the anterior
division of the fifth chamber, from parts of the delicate septa dividing
this from the four small sacs, corresponding with the insertions of the
glandular bodies above described.

In fact, on distending the vena cava with air, it is found that the four
branchial arteries traverse these septa, and that the appendages in
question are diverticula of their walls. Consequently the anterior wall
of each branchial vein is produced into two glandular appendages, which
hang into one of the four smaller sacs, while the posterior wall is
produced into a single mass of appendages, which hangs into the anterior
division of the fifth chamber.

Although, as I believe, the five chambers do not communicate directly,
all the appendages must nevertheless be equally bathed with sea-water,
which enters by the apertures of the chambers.

An impacted yellowish-white concretionary matter filled the anterior
chamber; and a small quantity of it lay as a fine powder at the bottom
of the posterior one. In the latter, however, its presence might, by
possibility, have been accidental. My colleague, Dr. Percy, who kindly
undertook to examine this substance,