MOLLUSCA. 
duct. It projects but a short way into the cavity of the Mollusea:. 
great bag, into which it empties its contents. These pass —\— = 
352 
Mollusca. and respire by means of gills or branchie. These are 
=~ double, one on each side, corresponding with the lateral 
pulmonic ventricles. Each gill is connected at its opposite 
sides to the tunic, by means of fleshy ligamentous bands. 
Between these, the double leaves of the gills are arranged 
in an alternate series. Each leaf is supported by a foot- 
stalk from the band, and is subdivided into smaller leaves, 
to expose a greater surface to the water. 
The pulmonary artery passes along this band, sends a 
branch into each footstalk, which, penetrating the substance 
of the gills, conveys the blood to its different divisions. 
The systemic veins depart from the gills at the opposite 
extremity. These unite at the inferior band, and from each 
gill a vessel proceeds to the single central or systemic heart 
or ventricle. In some of the animals of this class the sys- 
temic veins are somewhat enlarged, and assume the appear- 
ance of auricles. The two pulmonary, or rather the sys- 
temic veins, enter the heart at the opposite side, each at the 
termination being furnished with a valvular organization. 
The systemic heart is white and fleshy, and differs ac- 
cording to the genera, in its form, being in the Octopus se- 
micircular, but in the Loligo and Sepia lobed. Besides 
giving rise to a large aorta, or principal artery, two smaller 
ones likewise proceed from its cavity. These arteries are 
furnished at their entrance with valves. 
The sexes in the Cephalopoda are distinct, the male and 
female organs being found on different individuals. ‘There 
is not, however, any external mark by which they may be 
distinguished. M. Cuvier found that the males of the Oc- 
topus were scarcely a fifth part so numerous as the females. 
The male organs of generation consist of the following 
parts: The ¢esticle is a large white glandular purse, con- 
taining numerous fringed filaments, from which the seminal 
fiuid is secreted. This fluid passes out of the testicle by a 
valvular opening, into the vas deferens. This canal is slen- 
der, and greatly twisted in its course, and opens into a ca- 
vity which has been compared to the seminal vesicle. The 
walls of this last cavity are strong and muscular, and dis- 
posed in ridges. Near the opening at the distal extremity 
of this sac is an aperture leading into an oblong glandular 
body, regarded as exercising the functions of a prostate 
gland. Beyond this lies a muscular sac, divided at the top, 
where it opens by two ducts, but connected at the base. In 
this sac are numerous white thread-like bodies, terminated 
by a filament, but unconnected with the sac. In the in- 
terior they consist of a spiral body, connected at each ex- 
tremity with a glandular substance. When these bodies 
are put into water, they twist themselves in various direc- 
tions, and throw out at one of their extremities an opake 
fluid. These motions are not excited by placing them in 
oil or spirit of wine, but they may be exhibited by immers- 
ing in water those which have been kept for years in spirits. 
These bodies, first observed by Swammerdam, and after- 
wards by Needham, have been regarded by some as de- 
monstrating the truth of the vermicular theory of genera- 
tion; by others, they have been considered as analogous to 
the pollen of plants, their tunic is in part soluble in water, 
and when they are thrown into that fluid, they speed- 
ily burst, and spread their impregnating contents over the 
eggs of the female. Although this last conjecture is plau- 
sible, and countenanced by the circumstance that these ver- 
micular bodies are only found at the season of reproduction, 
the subject is still involved in obscurity. Are these bodies 
produced in the testicle, and only brought to this bag when 
nearly ready for exclusion; or, if the product of the bag 
itselt, by what means are they nourished ? 
The male organs terminate in a cylindrical fleshy body 
termed the Penis. This is hollow within, and ribbed with 
muscular bands. Near its base it receives one of the ducts 
of the vermicular sac, continuous with the one from the pros- 
tate gland, forming its canal, and toward the apex the other 
out of the body at the funnel-form opening in the throat. 
The female organs of generation consist of an ovariumt 
and oviduct. The ovarium is a glandular sac, to which the 
ova are attached by footstalks. The opening by which they 
issue from the ovarium is wide, and the oviduct (in the Oc- 
topus vulgaris and Loligo sagittata,) after continuing a 
short way simple, divides into two branches, each haying 
its external aperture near the anus. The oviducts are fur- 
nished within with muscular bands and a mucous lining, and 
encircled with a large glandular zone, destined, probably, 
to secrete the integuments of the eggs. In the Loliga vul- 
garis, and the Sepia, the oviduct continues single. Be- 
sides these organs, the Loliga vulgaris and sagittata, and 
the Sepia, have two large oval glandular bodies, divided by 
transverse partitions, with their excretory ducts terminating 
at the anus, the use of which is unknown. The eggs, of 
the peculiar form already noticed, pass out of the funnel, 
after which they are supposed to be impregnated by the 
male, according to the manner of fishes. 
The inky jduid now remains to be considered, as the most 
remarkable of the productions of this tribe of animals. The 
organ in which this fluid is secreted is spongy and glandu- 
lar. In some species it is contained in a recess of the liver, 
which has given rise to the opinion, that the coloured Auid 
which it secreted was bile. In other species, however, this 
gland is detached from the liver, and either situate in front 
or beneath that organ. The excretory canal of this gland 
opens in the rectum, so that the fluid escapes through the 
funnel. It mixes readily with water, and imparts to it its 
own peculiar colour. When dried, it is used as a pigment, 
and is considered as the basis of China ink. It is regarded 
by Signior Bezio as a peculiar substance which he has de~ 
nominated Melaina. It is obtained by digesting the ink 
with very dilute nitric acid, until it become yellowish, wash- 
ing it well, and separating it by the filter ; it is then to be 
frequently boiled in water, one of the washings to be a lit- 
tle alkalized; and, finally, with distilled water. The me- 
laina is.a tasteless, black powder, insoluble in alcohol, ether, 
and water, whilst cold, but soluble in hot water; the solu- 
tion is black. Caustic alkalis form with it a solution even 
in the cold, from which the mineral acids precipitate it un- 
changed. It contains much azote. It dissolves and de- 
composes sulphuric acid. It easily kindles in the fame of 
acandle. It has been found to succeed as a pigment in 
some respects, better than China ink. (Dud. Phil. Trans. 
Nov. 1825.) 
The Cephalopoda are all inhabitants of the sea. They 
are widely distributed, occurring in the arctic as well as the 
equatorial seas. In the latter, however, they grow to the 
largest size. It is reported, that in the Indian seas, boats 
have been sunk by these animals affixing to them their long 
arms, and that they are dreaded by divers. 
The two Linnean genera, Nautilus and Sepia, compre-. 
hend all the animals which are at present considered as be- 
longing to this class. 
Orver I.—NAvUTILACEA. 
Furnished with a multilocular shell. 
This order is involved in the greatest obscurity. None 
of the recent species have been subjected to an accurate, 
examination, so that their connection with the order Sepia- 
cea may still be considered doubtful. Enough is known of 
the animals of two of the genera, to furnish some hints for, 
those who are fond of classifying animals from their analo- 
gies. These genera are SprruLa and Naurizus. 
In the Spirzla, the shell, which is concealed under the 
skin of the back, is spixal, with the whorls separate, the 
mouth orbicular, the chambers perforated by a pipe, and 
