Class J. Cephalopoda. 
Order I. Tetrabranchiata. 
Il. Debranchiata. 
Class I]. Heteropoda. 
Class III. Pteropoda. 
Class IV. Gastropoda. 
Order I. Branchiata. 
Il. Pubnonata. 
Class V. Lamellibranchiata. 
Class I. Cephalopoda. 
Plate XX (left side). 
The Cuttle-fish have a well-defined head, sur- 
rounded with a series of sucker-bearing arms. They 
have eyes resembling those of vertebrate animals, 
which distinguish them at once from all other Mol- 
lusca. On the abdominal surface of the body is 
situated the funnel, through which ink is discharged 
in some species. The shell is often absent or con- 
cealed, and the mouth is armed with naked horny 

jaws, like the beak of a parrot reversed. The sexes 
are separate, and one arm of the male is modified 
into a copulatory organ, and is frequently so greatly 
modified that it preserves its power of motion for a 
long time, and was formerly supposed to be a distinct 
animal, and described under the name ‘‘Hectocotylus’’. 
The Cuttle-fish breathe by gills, of which there are 
either two or four. 
Order I. 
These Cuttle-fishes are provided with four gills 
and many movable tentacles on the head without 
suckers. They were a very important group in the 
former history of the world, and their petrified shells 
are known everywhere under the name of Ammonites. 
They are represented now by a single genus. 
Fig. a & b. Nautilus pompilius, the Pearly 
Nautilus, is figured entire and in section. The section 
shows it to consist of separate divisions (chambers). 
Order II. 
These are now represented by a large number 
of living genera and species. Instead of tentacles, 
the head is surrounded 
by 8 or 10 sucker-bear- 
ing arms. A few forms | 
only possess a_ shell, 
which is generally 
covered with the mantle. 
Most of them are pro- 
vided with a horny or 
calcareous plate on the 
back, the cuttle-bone. 
They have the pecu- 
liarity of changing their 
colour, and pass rapidly 
through a whole series 
of changes; red, blue, 
yellow and dusky. All 
the Dibranchiata are 
furnished with a peculiar 
organ called the ink-bag, 
which secretes a deep 
black fluid, from which 
the black pigment 
known as Sefza is pre- 
pared. 
Fig. c, Sepia officinalis, the Common Cuttle- 
fish, belongs to the group with 10 arms, of which 

Lolizo Brogniarti. 


Tetrabranchiata. 
The outermost is inhabited by the animal, and the 
others are filled with air, but they are all connected 
by a tube-like process called the Siphon, which 
penetrates the walls of separation. The shells of 
the extinct ammonites are constructed in a similar 
manner, and in these lines of growth of the walls 
of separation with the shell often exhibit very 
delicate moss-like ramifications. 
two are considerably longer than the others. The 
allied genus Loézgo is distinguished by its horny shell 
and long body. We have figured Loizgo Lroguiart. 
Another species, Lolzgo vulgaris, is eaten by the 
lower classes in Italy. 
The species of Sefza and Lolzgo are mostly 
coast animals, though they can swim well; but there 
are other Cuttle-fish, some of gigantic size, which 
inhabit the open sea. The fossils called ‘‘Belemnites”’ 
are the bones of extinct species of 10-armed Lz- 
branchiata. here is another group on which the 
two long arms found in Sefza &c. are absent. They 
have only 8 strong sucker-bearing arms, with which 
they seize their prey, and they do not hesitate to 
attack and destroy animals such as lobsters, which 
would seem to be much stronger than themselves. 
They generally hide in clefts of the rock, and dart 
out like lightning to seize their prey. In swimming 
the hinder end of the animal is moved forwards. 
Fig. d. Octopus vulgaris is typical of the 
8-armed Cuttle-fishes, 
Fig. e. Argonanta argo, the Paper Nautilus, 
is one of the few Dibranchiata which possesses a 
shell. This, however, is met with in the female only; 
the male is smaller, and is without it. The animal 
itself is very handsome when it grasps the delicate 
paper-like shell with the fin-like expansions on the 
back of the arms, It inhabits the Mediterranean. 
