4 
been removed or reflected backwards ; in this manner the branchial 
cavity is visible (fig. 4). 
The two overlapping sides of the funnel form a striking particularity 
of the structure of the Nautilus. It is interesting that the embryo 
in the dibranchiate group, as we learn from Dr. Kolliker’s observa- 
tions*, shows the funnel composed in the beginning of two lateral 
separate parts. The embryonic condition in the dibranchiate Ce- 
phalopods proves thus to be a persistent structure in the tetrabran- 
chiate group. 
Between the basal part of the second pair of gills the anal aperture 
is visible. This part has been misrepresented by Prof. Valenciennes. 
It seems that a longitudinal fold connecting the integuments of the 
viscera with the two large shell-muscles was disrupted in his specimen, 
and that the author believed this to be the rectum. The oviduct in 
this supine position is situated at the left side, before the anus, and 
terminates with a transverse bilabiated and protuberant aperture or 
vulva. [Consequently, when the animal is in its natural position in 
the shell, the termination of the oviduct lies at the right side. | 
There are three little slits on each side at the roots of the branchize. 
The first pair of those apertures is situated at the anterior surface of 
the first branchia, near the posterior margin of the large shell-muscle. 
Between the first and second branchie are the two other slits, very 
near to each other, and at the outward side of them is a little de- 
pressed papilla, affixed to the posterior surface of the root of the first 
branchia. The first and the last slits are the exterior openings of 
two lateral blind sacs, containing the follicular appendages of the 
branchial arteries; the second slit communicates with the pericar- 
dium+. At the first slit I once found a calcareous reddish-white and 
friable concrement ; I believed it to contain uric acid, but the chemical 
inquiry of my friend Prof. Van der Boonchesch has not confirmed my 
supposition. 
Behind the anus there are on each side two small and depressed 
caruncles, very similar to that mammillary eminence or papilla we 
have seen at the root of the first branchia. External to those carun- 
cles and behind them is a series of small orifices, not unlike to the 
openings of the Meybomian follicles on the human eyelids. These 
are the emunctories of the glandular organ, for the secretion of the 
covering matter of the ova. 
* Entwickelungsgeschichte der Cephalopoden. Von Dr. A. Kolliker; Zurich, 
1843, 4to, p. 41 ete. 
+ The three pairs of openings have been first observed by Prof. Valenciennes. 
This point of the anatomy of the Nautilus has been chiefly elucidated by the ob- 
servations of my friend Prof. W. Vrolik (Tijdschrift voor de natuurkundige Weten- 
schappen, uitgegeven door de Eerste Klasse van het Koninklijk-Nederlandsche In- 
stituut, ii. 1849, p. 312-315). Prof. Owen describes in his memoir but one of those 
openings, and it is therefore questionable what opening he speaks of. It seems 
however to me to be the second, because Prof. Owen describes the mammillary 
eminence which is nearest to this slit, and chiefly because the author observes 
that the orifice “‘ conducts from the branchial cavity to the pericardium.”’ (Memoir 
on the Nautilus, p. 27.) 
