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act as sails and that the other arms are used as oars was not based on any actual observation of the living animal, and it is now known that although the animal floats at the surface it does not See also:

SAIL

sail, the expanded arms being applied to the exterior surface of the See also:

shell, which is secreted by them. The eggs are carried in the shell, and as this structure is entirely absent in the See also:

MALES

males, there is See also:

GOOD, JOHN MASON (1764-1827)

good See also:

REASON (Lat. ratio, through French raison)

reason to conclude that the habit of carrying the eggs and using one pair of arms for that purpose gave rise to the modification of those arms and the secretion of the shell by them. See also:

HUXLEY, THOMAS HENRY (1825–1895)

Huxley once expressed the truth of the See also:

MATTER

matter with characteristic felicity in the remark that if the shell of the Argonaut is to be compared to anything of human invention or construction at all, it should be compared, not to a See also:

SHIP

ship or See also:

BOAT (0. Eng. bdt; the true etymological connexion with Dutch and Ger. boot, Fr. bateau, Ital. battello presents great difficulties; Celtic forms are from O. Eng.)

boat, but to a perambulator. The shell of Argonauta (see fig. 1) is spirally coiled and symmetrical, and thus bears a remarkable resemblance to the shell of the pearly nautilus and the See also:

EXTINCT

extinct See also:

AMMONITES

ammonites, especially r.a. Tr, See also:

FLOAT (in O. Eng. floc and flota, in the verbal form f eotan; the Teutonic root is flut-, another form of flu-, seen in " flow," cf. " fleet "; the root is seen in Gr. a-M e, to sail, Lat. pluere, to rain; the Lat, fluere and fluctus, wave, is not connect

Float; Br.a, ventral or posterior arms; Br.p, dorsal or anterior arms; V, the expanded portion of them, once called the sails; B, the See also:

BEAK (early forms beke and becke, from Fr. bec, late Lat. beccus, supposed to be a Gaulish word; the Celtic bec and beq, however, are taken from the English)

beak; C, the shell; En, the See also:

FUNNEL (through an O. Fr. founil, found in Breton, from Lat. infundibulum, that through which anything is poured, from fundere, to pour)

funnel. as it is like that of the pearly nautilus coiled towards the dorsal or anterior surface of the animal. It is ornamented by ridges and furrows which pass in transverse curves from the inner to the See also:

OUTER

outer margin of the coils. The outer margin or See also:

KEEL

keel is some-what flattened and the whole shell is compressed from See also:

side to side.

It differs entirely from the shell of the pearly nautilus in the See also:

ABSENCE (Lat. absentia)

absence of See also:

INTERNAL

internal septa and siphuncle and in the absence of any See also:

ATTACHMENT

attachment between it and the See also:

BODY

body. It is in fact entirely different in origin and relations to the body from the typical molluscan shell secreted by the See also:

MANTLE

mantle in other Cephalopods and other types of See also:

MOLLUSCA

Mollusca. It is a structure sui generis, unique in the whole phylum of Mollusca. The only description of the living animal by a competent observer which we have is that of Lacaze Duthiers, made on a single specimen on the Mediterranean See also:

COAST (from Lat. costa, a rib, side)

coast of See also:

France, and published in 1892, and even this is in some respects incomplete. The specimen after See also:

CAPTURE (from Lat. capere, to take; Fr. prise maritime; Ger. Wegnahme)

capture was carried in a bucket, and became separated from its shell. When placed with the shell in a large See also:

AQUARIUM (plural aquaria)

aquarium tank the animal resumed See also:

possession of the shell and assumed the attitude shown in fig. 1. The shell floated at the surface, doubtless in consequence of the inclusion of some See also:

air in the cavity of the shell. It is not known with certainty that the animal is able in its natural See also:

state to descend below the surface; the specimen here considered never did so of its own See also:

ACCORD (from Fr. accorder, to agree)

accord, and when pushed down always See also:

rose again. The See also:

SIPHON, or SYPHON (Lat. sipho; Gr. vi4xov, a tube)

siphon or funnel is unusually large and prominent, and is the See also:

CHIEF (from Fr. chef, head, Lat. caput)

chief or only See also:

ORGAN

organ of locomotion, the water which is expelled from it See also:

DRIVING (from " to drive," i.e. generally to propel, force along or in, a word common in various forms to the Teutonic languages)

driving the animal backwards. The arms are usually turned backwards and carried inside the shell, to the inner surface of which the suckers adhere, but one or two arms are from See also:

time to time extended in front. This does not apply to the dorsal arms which are applied to the outside of the shell, and the expanded membrane of these arms covers the greater See also:

PART

part of its surface.

The dorsal arms are turned backwards, and each is See also:

TWISTED

twisted so that the oral surfaces See also:

FACE (from Lat. fades, derived either from facere, to make, or from a root fa-, meaning " appear "; cf. Gr. cbatvstv)

face each other and the suckers are in contact with the shell. The membrane or velum is thin, and is really a See also:

GREAT

great expansion of a dorsal membrane similar to that which is found along the median dorsal See also:

LINE

line of the two posterior arms. The suckers of the originally posterior See also:

SERIES (a Latin word from serere, to join)

series of each dorsal See also:

ARM (a common Teutonic word; the Indo-European root is ar, to join or fit; cf. the Lat. armus, shoulder, and the plural word arma, weapons, Gr. apphs, joint, and the reduplicated apapilKSV, to join)

arm See also:

lie along the See also:

EXTERNAL

external border of the shell, and the arm with its two rows of suckers extends See also:

ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

round the whole border of the membrane, the arm being curved into a See also:

COMPLETE

complete See also:

LOOP

loop, so that its extremity reaches almost to the origin of the membrane near the See also:

BASE

base of the arm, the extremity being continued on to the internal surface of the membrane. The external See also:

ROW, JOHN (c. 1525—1580)

row of suckers, originally the posterior row, are See also:

UNITED

united by membrane which is continuous with the velum. The smaller suckers on the more distal part of the arm, which extends along the edge of the shell-See also:

APERTURE (from Lat. aperire, to open)

aperture, are quite sessile. In the figure of Lacaze-Duthiers (fig. 1) the suckers appear to be turned away from the shell, but this is erroneous. A figure showing the natural position is given in the Monograph of the Cephalopoda in the series of Monographs issued by the Zoological Station of See also:

Naples. The animal described by Lacaze-Duthiers lived a fortnight in captivity, during which time it devoured with avidity small fishes which were presented to it, seizing them, not by throwing out all the ventral arms, but by means of the suckers near the mouth. Judging from these observations, Argonauta is a pelagic animal which lives and feeds near the surface of the ocean. Several See also:

SPECIES

species of Argonauta are known, distributed in the tropical parts of all the great oceans. The male is much smaller than the See also:

FEMALE

female, not exceeding an See also:

INCH (O. Eng. ynce from Lat. uncia, a twelfthpart; cf. " ounce," and see As)

inch or so in length.

It secretes no shell and its dorsal arms are not modified. The third arm on the See also:

LEFT

left side, however, is modified in another way in connexion with See also:

REPRODUCTION

reproduction. Argonauta is one of the Cephalopods in which the See also:

PROCESS

process known as •hectocotylization of one arm is See also:

DEVELOPED

developed to its extreme degree, the arm affected becoming ultimately detached and left by the male in the mantle cavity of the female where it retains for some time its See also:

LIFE

life and See also:

POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power of See also:

MOVEMENT

movement. The hectocotylus or copulatory arm in the Argonaut is developed at first in a closed cyst (fig. 2), which afterwards bursts, allowing the arm to uncoil; the remains of the cyst See also:

FORM (Lat. forma)

form a See also:

sac on the back of the arm which serves to contain the spermatophores. The animal known as the Pearly Nautilus was unknown to the ancient Greeks, since its See also:

HABITAT (a French word derived from habiter, Lat. habitare, to dwell)

habitat is the seas of the far See also:

East, but in the See also:

MIDDLE

middle ages, when its shell became known in See also:

EUROPE

Europe, it was called, from its superficial similarity to that of the See also:

ORIGINAL

original nautilus, by the same name. It was See also:

LINNAEUS

Linnaeus who, in See also:

order to distinguish the two animals, took the name " nautilus " from the animal to which it originally belonged and bestowed it upon the very different East See also:

INDIAN

Indian Mollusc, giving to the original nautilus the new name Argonauta. Zoological nomenclature See also:

DATES

dates from Linnaeus, and thus the nautilus is now the name of theonly living genus of Tetrabranchiate Cephalopods. A detailed description of this animal is given in the See also:

ARTICLE (from Lat. articulus, a joint)

article Cephalopoda (q.v.); it is only necessary to add here a brief See also:

account of its mode of life and habits. Four species are known from the Indian and Pacific oceans; they are gregarious and nocturnal animals living at some See also:

DEPTH

depth and apparently always on the bottom. The natural attitude of the animal as represented by Dr Willey is with the oral surface down-wards, the tentacles spread out, and the shell See also:

VERTICAL (from Lat. vertex, highest point)

vertical. The See also:

chambers of the shell have no communication with one another nor with the siphuncle. they are air-tight cavities and filled, not with water, but with a nitrogenous See also:

gas.

This necessarily very much reduces the specific gravity of the animal, but it is still heavier than the water and does not seem capable of rising to the surface any more than an See also:

OCTOPUS (Gr. brcreo, eight and gobs, foot)

octopus. Nautilus is rather abundant at some localities in the East Indian See also:

ARCHIPELAGO

Archipelago, for example at See also:

AMBOYNA (Dutch Ambon)

Amboyna in the See also:

MOLUCCAS, or SPICE ISLANDS

Moluccas. In 1901–1902 Dr See also:

Arthur Willey of See also:

Cambridge University spent some time in that region for the purpose of investigating the reproduction and development of the animal. He stationed himself at New See also:

BRITAIN (Gr. Hperavuml vi7vot, Bperravia; Lat. Britannia, rarely Britannia)

Britain, known to the Germans as Neu Pommern, an See also:

ISLAND (O.E. ieg =isle, +land')

island of the See also:

Bismarck Archipelago off the coast of Papua. The natives of this island use the nautilus for See also:

food, capturing them by means of a large See also:

fish-See also:

TRAP (0. Eng. treppe or traepee, properly a step, as that or which an animal places its foot and is caught, cf. Ger. Treppe flight of stairs)

trap similar in construction to the cylindrical See also:

LOBSTER (O.E. lopustre, lopystre, a corruption of Lat. locusta, lobster or other marine shell-fish; also a locust)

lobster-traps used by See also:

BRITISH

British fishermen. Fish is used for bait. Dr Willey found the males much more numerous than the See also:

FEMALES

females; of fifteen specimens captured on one occasion only two were females. He kept specimens alive both in vessels on See also:

SHORE

shore and in large baskets moored at the bottom of the sea. He found that when they were placed in a See also:

VESSEL (O. Fr. vaissel, from a rare Lat. vascellum, dim. of vas, vase, urn)

vessel of sea water See also:

numbers of a small parasitic See also:

CRUSTACEA

crustacea issued from the mantle cavity. Some of the females laid eggs in captivity, but these were found not to be fertilized; they were about 3.5 centimetres See also:

long and attached singly by a broad base to the sides of the cage in which the animals were confined.

End of Article: NAUTILUS

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