CEPHALIC INDEX, the term in use by anthropologists to express the
percentage of breadth to length in any skull. The principle employed by
Retzius is to take the longer diameter of a skull, the antero-posterior
diameter, as 100; if the shorter or transverse diameter falls below 80
the skull may be classed as long (dolichocephalic), while if it exceeds
80 the skull is broad (brachycephalic) (see CRANIOMETRY).
CEPHALONIA (Ital. _Cefalonia_, ancient and modern official Greek
_Cephallenia_, [Greek: Kephallênia]), an island belonging to the kingdom
of Greece, and the largest of those known as the Ionian Islands,
situated on the west side of the mainland, almost directly opposite the
Gulf of Corinth. The name was traditionally derived from Cephalus, the
Attic hero who was regarded as having colonized the island. The
tradition, which is repeated by Aristotle, is probably due solely to the
similarity of the names (see J.G. Frazer, _Pausanias_, i. 37, 6 note).
Pop. (1907) 71,235. Its extreme length is 31 m., and its breadth varies
from about 20 m. in the southern portion to 3 m. or less in the
projecting part, which runs parallel with the island of Ithaca, at a
distance of about 4 m. across the strait of Guiscardo or Viscaro. The
whole island, with its area of 348 English sq. m., is covered with rocky
hills of varying elevation, the main range running from north-west to
south-east. The ancient Mount Aenos, now Elato, Monte Negro, or the
Black Mountain (5315 ft.), frequently retains the snow for several
months. It is not only the loftiest part of the sierra, but also the
highest land in the whole Ionian group. The name "Black" was given from
the darkness of the pine woods which still constitute the most striking
feature in Cephalonian scenery, although their extent has been greatly
curtailed by fire. The summit is called Megálo Sorós. The island is ill
supplied with fresh water; there are few permanent streams except the
Rakli, and springs are apt to fail in dry summers. In the western part
of the island a gulf runs up from the south, a distance of about 7 m.;
on its east side stands the chief town Argostoli, with about 10,000
inhabitants, and on its west side the rival city of Lixouri, with 6000.
About a mile west of the town are the curious sea mills; a stream of sea
water running down a chasm in the shore is made to turn the wheels.
About 5 m. from Argostoli is the castle of St George, a building of
Venetian origin, and the strongest fortification in the island. On an
eminence east-south-east of Argostoli are the ruins of the ancient
Cranii, and Lixouri is close to or upon those of Pale; while on the
other side of the island are the remains of Samos on the bay of the same
name, of Proni or Pronni, farther south above the vale of Rakli and its
blossoming oleanders, and of an unknown city near the village of Scala.
The ruins of this city include Roman baths, a brick-built temple,
rock-cut tombs, and tessellated pavements; and Cranii, Proni and Samos
are remarkable for stretches of Cyclopean and Hellenic walls, partly of
the most irregular construction, and partly preserving almost unimpaired
the results of the most perfect skill. The inhabitants of Cephalonia
have all along been extremely active; and no slight amount of toil has
been expended in the construction of terraces on the steep sides of the
hills. Owing to the thinness of the population, however, but a small
proportion of the soil is under cultivation, and the quantity of grain
grown in the island is comparatively meagre. The staple is the currant,
in the production of which the island surpasses Zante. The fruit is
smaller than that of the Morea, and has a peculiar flavour; it finds a
market mainly in Holland, Belgium and Germany. The grape vine also is
grown, and the manufacture of wine is a rising industry. The olive crop
is of considerable importance, and the culture of cotton in the low
grounds has been successfully attempted. Manufactures are few and
undeveloped, but lace from the aloe fibre, Turkey carpets and
basket-work are produced by the villagers, and boats are built at both
the principal towns. Of all the seven Ionian islands Cephalonia and
Zante are most purely Greek, and the inhabitants display great mental
activity.
In the Homeric poems Cephalonia is generally supposed to be mentioned
under the name of Same, and its inhabitants, among the subjects of
Ulysses, to be designated Cephallenes (see, however, under ITHACA). In
the Persian War they took but little part; in the Peloponnesian they
sided with the Athenians. The town of Pale was vainly besieged by Philip
of Macedon in 218 B.C., because it had supported the Aetolian cause. In
189 B.C. all the cities surrendered to the Romans, but Same afterwards
revolted, and was only reduced after a siege of four months. The island
was presented by Hadrian to Athens, but it appears again at a later date
as "free and autonomous." After the division of the Roman empire, it
continued attached to Byzantium till 1082, when it was captured by
Robert Guiscard, who died, however, before he could repress the revolt
of 1085. In 1204 it was assigned to Gaius, prince of Tarentum, who
accepted the protection of Venice in 1215; and after 1225 it was held
along with Santa Maura and Zante by a succession of five counts of the
Tocco family at Naples. Formally made over to Venice in 1350 by the
prince of Tarentum, it was afterwards captured by the Turks in 1479; but
the Hispanico-Venetian fleet under Benedetto Pessaro and Gonsalvo of
Cordova effected their expulsion in 1500, and the island continued in
Venetian possession till the fall of the republic. For some time it was
administered for the French government, but in 1809 it was taken by the
British under Cuthbert, Lord Collingwood. Till 1813 it was in the hands
of Major de Bosset, a Swiss in the British service, who displayed an
industry and energy in the repression of injustice and development of
civilization only outdone by the despotic vigour of Sir Charles Napier,
who held the same office for the nine years from 1818 to 1827. During
the British protectorate the island made undoubted advances in material
prosperity, but was several times the scene of political disturbances.
It retained longer than the sister islands traces of feudal influence
exerted by the landed proprietors, but has been gradually becoming more
democratic. Under the Venetians it was divided into eight districts, and
an elaborate system of police was in force; since its annexation to
Greece it has been broken up into twenty demarchies, each with its
separate jurisdiction and revenues, and the police system has been
abolished.
AUTHORITIES.--A special treatise on the antiquities of Cephalonia was
written by Petrus Maurocenus. See Holland's _Travels_ (1815); Ansted's
_Ionian Islands_ (1863); Viscount Kirkwall's _Four Years in Ionian
Islands_ (1864); Wiebel's _Die Insel Kephalonia_; parliamentary
papers. Riemann, _Recherches archéologiques sur les Iles Ioniennes_
(Paris, 1879-1880); Partsch, _Kephallenia und Ithaka_ (1890); see also
CORFU; IONIAN ISLANDS. (E. Gr.)
CEPHALOPODA, the fifth of the classes into which the zoological phylum
Mollusca is divided (see MOLLUSCA). The Cephalopoda are mainly
characterized by the concrescence of the foot and head. The foot grows
forward on each side so as to surround the mouth, the two upgrowths
meeting on the dorsal side of the head--whence the name Cephalopoda. The
perioral portion of the foot is drawn out into paired arm-like
processes; these may be beset with sheathed tentacles or with suckers or
hooks, or both. The epipodia are expanded into a pair of muscular lobes
right and left, which are bent round towards one another so that their
free margins meet and constitute a short tube--the siphon or funnel. The
hind-foot is either very small or absent. A distinctive feature of the
Cephalopoda is their bilateral symmetry and the absence of anything like
the torsion of the visceral mass seen in the Anisopleurous Gastropoda.
The anus, although it may be a little displaced from the median line,
is approximately median and posterior. The mantle-skirt is deeply
produced posteriorly, forming a large sub-pallial chamber around the
anus. By the side of the anus are placed the single or paired
apertures of the nephridia, the genital apertures (paired only in
_Nautilus_, in female Octopoda, female _Ommatostrephes_ and male
_Eledone_), and the paired ctenidia. The visceral hump or dome is
elevated, and may be very much elongated in a direction almost at
right angles to the primary horizontal axis of the foot.
A shell is frequently, but not invariably, secreted on the visceral
hump and mantle-skirt. The shell is usually light in substance or
lightened by air-chambers in correlation with the free-swimming habits
of the Cephalopoda. It may be external or internal, that is, enclosed
in folds of the mantle. Very numerous minute pigmented sacs, capable
of expansion and contraction, and known as chromatophores, are usually
present in the integument. The sexes are separate.
The ctenidia are well developed as paired gill-plumes, serving as the
efficient branchial organs (figs. 4, 24),
The vascular system is very highly developed; the heart consists of a
pair of auricles and a ventricle (figs. 12, 28). Branchial hearts are
formed on the afferent vessels of the branchiae. It is not known to
what extent the minute subdivision of the arteries extends, or whether
there is a true capillary system.
The pericardium is extended so as to form a very large sac, passing
among the viscera dorsalwards and sometimes containing the ovary or
testis--the viscero-pericardial sac--which opens to the exterior
either directly or through the renal organs. It has no connexion with
the vascular system. The renal organs are always paired sacs, the
walls of which invest the branchial afferent vessels (figs. 28, 29).
They open each by a pore into the viscero-pericardial sac, except in
_Nautilus_. The anal aperture is median and raised on a papilla. Jaws
(fig. 6, e) and a radula (fig. 9) are well developed. The jaws have
the form of powerful beaks, either horny or calcified (_Nautilus_),
and are capable of inflicting severe wounds.
Cerebral, pleural and pedal ganglia are present, but the connectives
are shortened and the ganglia concentrated and fused in the cephalic
region. Large special ganglia (optic, stellate and supra-buccal) are
developed. Sense-organs are highly developed; the eye exhibits a very
special elaboration of structure in the Dibranchiata, and a remarkable
archaic form in the nautilus. Otocysts are present in all. The typical
osphradium is not present, except in _Nautilus_, but other organs are
present in the cephalic region, to which an olfactory function is
ascribed both in _Nautilus_ and in the other Cephalopoda.
Hermaphroditism is unknown in Cephalopoda; male and female individuals
always being differentiated. The genital aperture and duct is
sometimes single, when it is the left; sometimes the typical pair is
developed right and left of the anus. The males of nearly all
Cephalopoda have been shown to be characterized by a peculiar
modification of the arm-like processes or lobes of the fore-foot,
connected with the copulative function. The term hectocotylization is
applied to this modification (see figs. 6, 24). Elaborate
spermatophores or sperm-ropes are formed by all Cephalopoda, and very
usually the female possesses special capsule-forming and nidamental
glands for providing envelopes to the eggs (fig. 4, g.n.). The egg is
large, and the development is much modified by the presence of an
excessive amount of food-material diffused in the protoplasm of the
egg-cell. Trochosphere and veliger stages of development are
consequently not recognizable.
The Cephalopoda are divisible into two orders, Tetrabranchiata and
Dibranchiata, the names of which (due to Sir R. Owen) describe the
number of gill-plumes present; but in fact there are several characters,
of as great importance as those derived from the gills, by which the
members of these two orders are separated from one another.
ORDER 1. TETRABRANCHIATA (= Schizosiphona, Tentaculifera).
_Characters_.--The inrolled lateral margins of the epipodia are not
fused, but form a siphon by apposition (fig. 4). The circumoral lobes of
the fore-foot carry numerous retractile tentacles, not suckers (fig. 6).
There are two pairs of ctenidial gills (hence Tetrabranchiata), and two
pairs of renal organs, consequently four renal apertures (fig. 4). The
viscero-pericardial chamber opens by two independent apertures to the
exterior, and not into the renal sacs. There are two oviducts (right and
left) in the female, and two sperm-ducts in the male, the left duct in
both sexes being rudimentary. A large external shell, either coiled or
straight, is present, and is not enclosed by reflections of the
mantle-skirt. The shell consists of a series of chambers, the
last-formed of which is occupied by the body of the animal, the hinder
ones (successively deserted) containing gas (fig. 1). The pair of
cephalic eyes are hollow chambers (fig. 14. A), opening to the exterior
by minute orifices (pin-hole camera), and devoid of refractive
structures. A pair of osphradia are present at the base of the gills
(fig. 4, _olf_). Salivary glands are wanting. An ink-sac is _not_
present. Branchial hearts are _not_ developed on the branchial afferent
vessels.
[Illustration: FIG. 1.--Lateral view of the female Pearly Nautilus,
contracted by spirit and lying in its shell, the right half of which is
cut away (from Gegenbaur, after Owen).
a, Visceral hump.
b, Portion of the free edge of the mantle-skirt reflected on to the
shell,--the edge of the mantle-skirt can be traced downwards and
forwards around the base of the mid-foot or siphon i.
l, l, Superficial origin of the retractor muscle of the mid-foot
(siphon), more or less firmly attached to the shell, of which a small
piece (s) is seen between the letters l, l.
s, (farther back) points to the siphuncular pedicle, which is broken
off short and not continued, as in the perfect state, through the
whole length of the siphuncle of the shell, also marked s and s'.
o, points to the right eye.
t, is placed near the extremities of the contracted tentacles of the
outer or annular lobe of the fore-foot--the jointed tentacles are seen
protruding a little from their long cylindrical sheaths.
v, The dorsal "hood" formed by an enlargement in this region of the
annular lobe of the fore-foot (m in figs. 2, 3).
V, A swelling of the mantle-skirt, indicating the position on its
inner face of the nidamental gland (see fig. 4, g.n.).]
_Visceral Hump and Shell._--The visceral hump of _Nautilus_ (if we
exclude from consideration the fine siphuncular pedicle which it trails,
as it were, behind it) is very little, if at all, affected by the coiled
form of the shell which it carries, since the animal always slips
forward in the shell as it grows, and inhabits a chamber which is
practically cylindrical (fig. 1). Were the deserted chambers thrown off
instead of being accumulated behind the inhabited chamber as a coiled
series of air-chambers, we should have a more correct indication in the
shell of the extent and form of the animal's body. Amongst Gastropods it
is not very unusual to find the animal slipping forward in its shell as
growth advances and leaving an unoccupied chamber in the apex of the
shell. This may indeed become shut off from the occupied cavity by a
transverse septum, and a series of such septa may be formed, but in no
Gastropod are these apical chambers known to contain a gas during the
life of the animal in whose shell they occur. A further peculiarity of
the nautilus shell and of that of the allied extinct _Ammonites_,
_Scaphites_, _Orthoceras_, &c., and of the living _Spirula_, is that the
series of deserted air-chambers is traversed by a cord-like pedicle
extending from the centro-dorsal area of the visceral hump to the
smallest and first-formed chamber of the series. No structure comparable
to this siphuncular pedicle is known in any other Mollusca. The
siphuncle does not communicate with the coelomic cavity; it is a simple
vascular process of the mantle, whose cavity consists of a venous sinus,
and whose wall contains a ramification of the pallial artery. There
appears to be no doubt that the deserted chambers of the nautilus shell
contain in the healthy living animal a gas which serves to lessen the
specific gravity of the whole organism. This gas is said to be of the
same composition as the atmosphere, with a larger proportion of
nitrogen. With regard to its origin we have only conjectures. Each
septum shutting off an air-containing chamber is formed during a period
of quiescence, probably after the reproductive act, when the visceral
mass of the nautilus may be slightly shrunk, and gas is secreted from
the dorsal integument so as to fill up the space previously occupied by
the animal. A certain stage is reached in the growth of the animal when
no new chambers are formed. The whole process of the loosening of the
animal in its chamber and of its slipping forward when a new septum is
formed, as well as the mode in which the air-chambers may be used as a
hydrostatic apparatus, and the relation to this use, if any, of the
siphuncular pedicle, is involved in obscurity, and is the subject of
much ingenious speculation. In connexion with the secretion of gas by
the animal, besides the parallel cases ranging from the protozoon
_Arcella_ to the physoclistic fishes, from the hydroid _Siphonophora_ to
the insect-larva _Corethra_, we have the identical phenomenon observed
in the closely allied _Sepia_ when recently hatched. Here, in the pores
of the internal rudimentary shell, gas is observable, which has
necessarily been liberated by the tissues which secrete the shell, and
not derived from any external source (Huxley).
The coiled shell of _Nautilus_, and of the majority of extinct
Tetrabranchiata, is peculiar in its relation to the body of the animal,
inasmuch as the curvature of the coil proceeding from the centro-dorsal
area is towards the head or forwards, instead of away from the head and
backwards as in other discoid coiled shells such as _Planorbis_; the
coil is in fact absolutely reversed in the two cases. Such a shell is
said to be exogastric. But in some extinct forms, e.g. _Phragmoceras_,
_Cyrtoceras_, _Ptenoceras_, the shell is coiled towards the ventral
side, when it is termed endogastric. Amongst the extinct allies of the
nautilus (Tetrabranchiata) we find shells of a variety of shapes, open
coils such as _Scaphites_, leading on to perfectly cylindrical shells
with chamber succeeding chamber in a straight line (_Orthoceras_),
whence again we may pass to the corkscrew spires formed by the shell of
_Turrilites_. In some extinct genera, e.g. _Gomphoceras_, among the
Nautiloidea the aperture of the shell is contracted and the edge of the
aperture is lobed. In these cases the animal was probably able only to
protrude its appendages and not its whole head. The ventral part of the
aperture corresponding to the funnel is separated from the dorsal part
by a constriction. Hence it is possible to distinguish the ventral and
dorsal sides of the shell and to decide whether it was exogastric or
endogastric. The direction of the coil of the shell cannot be determined
by the position of the siphuncle, which traverses the septa centrally,
ventrally or dorsally. Contracted shell apertures occur also in
Ammonitoidea, the condition reaching an extreme in _Morphoceras_, where
the original aperture is subdivided by the ingrowth of the sides, so
that only five small separate apertures remain. Of these the central
probably corresponded to the mouth, two lateral to the eyes, and the
remaining two to the pedal appendages.
_Head, Foot, Mantle-skirt and Sub-pallial Chamber._--In the pearly
nautilus the ovoid visceral hump is completely encircled by the free
flap of integument known as mantle-skirt (figs. 2, 3, d, e). In the
antero-dorsal region this flap is enlarged so as to be reflected a
little over the coil of the shell which rests on it. In the
postero-ventral region the flap is deepest, forming an extensive
sub-pallial chamber, at the entrance of which e is placed in fig. 3. A
view of the interior of the sub-pallial chamber, as seen when the
mantle-skirt is retroverted and the observer faces in the direction
indicated by the reference line passing from e in fig. 3, is given in
fig. 4. With this should be compared the similar view of the
sub-pallial chamber of the Dibranchiate _Sepia_. It should be noted as
a difference between _Nautilus_ and the Dibranchiates that in the
former the nidamental gland (in the female) lies on that surface of
the pallial chamber formed by the dependent mantle-flap (fig. 4, g.n.;
fig. 1, V), whilst in the latter it lies on the surface formed by the
body-wall; in fact in the former the base of the fold forming the
mantle-skirt comprises in its area a part of what is unreflected
visceral hump in the latter.
[Illustration: FIG. 2.--Spirit specimen of female Pearly Nautilus,
removed from its shell, and seen from the antero-dorsal aspect (drawn
from nature by A.G. Bourne).
m, The dorsal "hood" formed by the enlargement of the outer or
annular lobe of the fore-foot, and corresponding to the sheaths of
two tentacles (g, g in fig. 6).
n, Tentacular sheaths of lateral portion of the annular lobe.
u, The left eye.
b, The nuchal plate, continuous at its right and left posterior
angles with the root of the mid-foot, and corresponding to the
nuchal cartilage of Sepia.
c, Visceral hump.
d, The free margin of the mantle-skirt, the middle letter d points
to that portion of the mantle-skirt which is reflected over a part
of the shell as seen in fig. 1, b; the cup-like fossa to which b and
d point in the present figure is occupied by the coil of the shell.
g.a. points to the lateral continuation of the nuchal plate b to
join the root of the mid-foot or siphon.]
[Illustration: FIG. 3.--Lateral view of the same specimen as that
drawn in fig. 2. Letters as in that figure with the following
additions--
e, points to the concave margin of the mantle-skirt leading into the
sub-pallial chamber.
g, The mid-foot or siphon.
k, The superficial origin of its retractor muscles closely applied
to the shell and serving to hold the animal in its place.
l, The siphuncular pedicle of the visceral hump broken off short.
v, v, The superior and inferior ophthalmic tentacles.]
The apertures of the two pairs of renal sacs, of the
viscero-pericardial sac, of the genital ducts, and of the anus, are
shown in position on the body-wall of the pallial chamber of
_Nautilus_ in figs. 4, 5. There are nine apertures in all, one median
(the anus) and four paired. Besides these apertures we notice _two_
pairs of gill-plumes which are undoubtedly typical ctenidia, and a
short papilla (the osphradium) between each anterior and posterior
gill-plume (see figs. 4, 5, and explanation). As compared with this in
a Dibranchiate, we find (fig. 25) only four apertures, viz. the median
anus with adjacent orifice of the ink-sac, the single pair of renal
apertures, and one asymmetrical genital aperture (on the left side)
except in female Octopoda and a few others, where the genital ducts
and their apertures are paired. No viscero-pericardial pores are
present on the surface of the pallial chamber, since in the
Dibranchiata the viscero-pericardial sac opens by a pore into each
nephridium instead of directly to the surface. A single pair of
ctenidia (gill-plumes) is present instead of the two pairs in
_Nautilus_. The existence of two pairs of ctenidia and of two pairs of
renal sacs in _Nautilus_, placed one behind the other, is highly
remarkable. The interest of this arrangement is in relation to the
general morphology of the Mollusca, for it is impossible to view this
repetition of organs in a linear series as anything else than an
instance of metameric segmentation, comparable to the segmentation of
the ringed worms and Arthropods. The only other example which we have
of this metamerism in the Mollusca is presented by the Chitons. There
we find not two pairs of ctenidia merely, but sixteen pairs (in some
species more) accompanied by a similar metamerism of the dorsal
integument, which carries eight shells. In _Chiton_ the renal organs
are not affected by the metamerism as they are in _Nautilus_. It is
impossible on the present occasion to discuss in the way which their
importance demands the significance of these two instances among
Mollusca of incomplete or partial metamerism; but it would be wrong to
pass them by without insisting upon the great importance which the
occurrence of these isolated instances of metameric segmentation in a
group of otherwise unsegmented organisms possesses, and the light
which they may be made to throw upon the nature of metameric
segmentation in general.
[Illustration: FIG. 4.--View of the postero-ventral surface of a
female Pearly Nautilus, the mantle-skirt (c) being completely
reflected so as to show the inner wall of the sub-pallial chamber
(drawn from nature by A.G. Bourne).
a, Muscular band passing from the mid-foot to the integument.
b, The valve on the surface of the funnel, partially concealed by
the inrolled lateral margin of the latter.
c, The mantle-skirt retroverted.
an, The median anus.
x, Post-anal papilla of unknown significance.
g.n., Nidamental gland.
r.ov, Aperture of the right oviduct.
l.ov, Aperture of the rudimentary left oviduct (pyriform sac of
Owen).
neph.a, Aperture of the left anterior renal sac.
neph.p, Aperture of the left posterior renal sac.
viscper, Left aperture of the viscero-pericardial sac.
olf, The left osphradium placed near the base of the anterior
gill-plume.