Cephalopoda. MOLLL’SCA. Decapoda 
314 
careoiis. Tlie head is smaller than the body, and the 
eyes are free in the orbit, turning in every direction in 
the very large orbital cavity. The arms are usually 
said to be ten in number — hence their name of Deca- 
pods. Two of these, however, differ considerably in 
their form from the others, and by many conchologists 
are termed tentacles. The real arms are eight in 
number, as in the Octopods, but are always shorter; 
they are fleshy, sessile, and often edged with mem- 
branes. The two tentacular arms are long, cylindrical 
and are expanded at the ends. The cups or suckers 
are oblique, peduncled, and armed with a hornj'' ring. 
The siphuncle is almost always provided with an 
internal valve. The animals belonging to this sub- 
order are chiefly found in the open sea, but, it is said, 
make their appearance periodically in large shoals, like 
certain Ashes, on the coasts and banks. The structure 
of the internal shell is well adapted for dividing the 
species of Decapods into three distinct groups or sec- 
tions — those which have a solid horny shell, like a 
pen {gladius), Chondkophoka ; those which have a 
cellular calcareous shell {sepion), Sefiophora; and 
lastly, those which have a chambered, siphoned shell, 
(in recent species) calcareous or shelly, Belemxo- 
PHORA. 
Section I.— CHONDROPHORA. 
This section contains flve families, but we have 
only space to mention two : — 
Family I.— CPIIROTEUTHID^. 
The animals of this family are semipellucid, and 
have an elongate body, and the Ans are placed on the 
Hinder part of the back. The ventral arms are long, 
and the tentacular arms are external to the web, very 
long and slender, and not retractile into the cavities 
under the orbits. On the peduncular portion they 
have distant sessile cups, but on their expanded ends 
they possess four rows of cups placed on long cylin- 
drical peduncles. The siphuncle has no valve. The 
shell is elongated and slender. 
Genus Chiroteutiiis. — The genus Chiroteutlds 
will represent the family. It has the arms free ; the 
rings of the cups are contracted in the middle. The 
tentacular arms are extremely elongated, and the cups 
on their ex|)anded ends are placed on long cjdindrical 
peduncles swollen at the end, and bear a second pedicle 
which carries a hood like horny ring, edged at the 
base, with a lateral aperture armed with teeth. The 
shell is very slender, and slightly dilated into a narrow 
lanceolate expansion at each end. 
CHIROTEUTHIS VERANYI, one of the species, is a 
native of the Mediterranean. The body is scarcely 
four inches in length, while the tentacular arms are two 
feet and a half, and as slender as a thread. The habits 
of this animal appear in a great measure unknown; but, 
as has been well observed, a similar disproportion of 
parts is not to be found exampled among organized 
creatures. “ How these slender organs are moved,’' 
says Dr. .Johnston — “how their motions are propagated 
along the lengthened line — how the club at the end of 
such a flexible line is supported— and how the organs 
are preserved from amputation or injury — are all 
questions which start upon us as we contemplate the 
creature, and to which it is not easy to give a satis- 
factory answer.” They are no doubt intended, and 
certainly appear admirably adapted for securing their 
prey, especially such as may be floating careless at a 
distance, and unconscious of danger from such a foe. 
Family II.— ONYCHOTEUTHIDHH {Uncinated 
Calamaries). 
This family consists of animals with an elongate fleshy 
body, furnished with Ans on^ie hinder part of the back. 
The head is cylindrical in shape, and the eyes are naked, 
with a deep lachrymal sinus at the upper edge. The 
siphuncle has a distinct internal valve, and the ten- 
tacular arms have a rounded group of small sessile cups 
at their dilated extremities. The shell is lanceolate. 
One of the most striking characters of this family is the 
structure of the long tentacular arms and their suckers. 
These organs are provided with a double series of 
hooks; but besides these uncinated cups there is, 
as mentioned above, at the base of their expanded 
extremities a cluster of small, simple, unarmed cu[)s. 
These they are supposed to unite, so that the tentacles 
are used in conjunction. “ When these suckers are 
applied to one another,” says Professor Owen, “the 
tentacles are flrmly locked together at that part, and 
the united strength of both the elongated peduncles can 
be applied to drag towards the mouth any resisting 
object which has been grappled by the terminal hooks. 
There is no mechanical contrivance which surpasses 
this structure : art has remotely imitated it in the 
fabrication of the obstetrical forceps, in which either 
blade can be used separately, or by the interlocking 
of a temporary joint be made to act in combination.” 
This family contains several genera, but we have only 
space to mention two ; — 
Genus Enoploteutiiis. — This genus has both the 
sessile and tentacular cups armed with claw-like hooks. 
It contains several species with an elongate body fur- 
nished with Ans on the hinder part of the back ; sessile 
arms with a series of closed, horny, claw-like hooks, 
enlarged at their base and covered with a closely-Atting 
retractile membrane ; tentacular arms slender, feeble, 
scarcely dilated at the ends, and armed with hooks only. 
Some of the species attain a large size, and the natives 
of the Polynesian islands, who dive for shell-Ash, are 
said to have a well-founded dread and abhorrence of 
tnese formidable creatures. A specimen of E. ungui- 
culata was observed by Banks and Solander, in Captain 
Cook’s flrst voyage, floating on the surface in the PaciAc 
Ocean, a single arm of which is preserved in the collec- 
tion of the Museum of the College of Surgeons, from 
which it is evident that the animal must have been at 
least six feet long. 
Genus Ommastrephes. — This genus is character- 
ized by having the body very long, acuminated behind, 
truncated and square in front, with very broad tormina’ 
Ans; sessile arms,with two rows of suckers having oblique, 
toothed rings ; tentacular arms short, thick, and strong, 
not retractile, webbed at the slightly enlarged extremity 
