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the lateral line, which scarcely extends .beyond the extremities of the pectoral lit IK.
The scales also are of a regular ovate form, without the distinct fan-like rays so
characteristic of the bleak.

The last member of this great subfamily that we shall mention
is the curious-looking fish (Pelecus cuUratus) shown in the upper
figure of the illustration on p. 465, known in Germany as the sichel, and forming
the sole representative of its genus. It is at once characterised by tin; whole of
the abdominal surface of the oblong and compressed body forming a sharp cutting
edge; the scales being small, and the lateral line making a sudden descent behind
the pectoral fin towards the lower surface. The cleft of the mouth is always
peculiar in having a nearly perpendicular direction. The pectoral fins are
unusually tall, and the dorsal is placed far back, and above the anal, which
resembles that of the bream in its numerous rays. On the pharyngeal bones the
teeth are arranged in a double series, and are strongly hooked. In profile this
fish, which generally ranges from 6 inches to a foot in length, is remarkable for
the straightness of the line of the back, and the convexity of its lower border. It
is widely distributed in Eastern Europe, being common in the Black and Caspian
seas, as well as in their affluent rivers. In form this fish makes a curious approach
to the members of the herring tribe.

With the small fishes known as loaches, of which there are three
European genera, we come to the second subfamily (Cdbitiiue) of
the carp tribe, which is characterised by the air-bladder being either partially or
entirely enclosed in a bony capsule; false gills being always absent. In these
fishes the body may be elongate, oblong, compressed, or cylindrical, but is never
depressed ; the muzzle and lips are fleshy ; and the small, inferiorly-placed mouth
is furnished with from six to twelve barbels. The median fins are spineless, the
dorsal having a variable number of rays, but the short anal possessing but few,
while the pelvic pair may be wanting ; scales small, rudimental, or absent, and when
present, cycloid, and usually immersed in mucus; in one Oriental genus, developed
upon the back and sides of the head. The loaches of this subfamily are confined
to Europe and Asia ; and while some of those from the former continent are
partial to swift clear streams with a stony bottom, the Indian forms delight in



CARP TRIBE.



467



muddy tanks, where they bury themselves in the mud. All are carnivorous ; and,
in spite of their small size, the European species are esteemed as food. The giant
loach (Misgurnus fossilis), forming the central figure of our illustration, is the
largest European member of the group, and belongs to a genus of four species,
common to Europe and Asia north of the Himalaya. The genus is characterised
by the elongate and compressed form of the body, the absence of an erectile spine
near the eye, and the presence of from ten to twelve barbels, four of which belong
to the lower jaw ; the dorsal fin being placed above the pelvic pair, and the caudal
rounded. The European species, which grows to a length of 10 inches, is found
in stagnant waters in Southern and Eastern Germany, and North- Western Asia ;



GIANT LOACH, COMMON LOACH, AND SPINY LOACH (* nat. .size).




being replaced by an allied form in China and Japan. The true loaches (Nema-
cftilus), on the other hand, have six upper barbels, and none on the lower jaw.
They are represented by some fifty species from Europe and Temperate Asia ; the
common British loach (N. barbatulus), shown in the upper figure of the illustration,
being found in clear streams all over Europe with the exception of Denmark and
Scandinavia. The spiny loach (Oobitis tcenia), shown in the lower corner of the
illustration, is the typical representative of a third genus, distinguished from the
last by the presence of a small, bifid, erectile spine below each eye. The figured
species is locally and sparingly distributed in Britain, but more common on the
Continent. Certain Indian loaches formerly included in this genus are now
regarded as distinct, the subfamily being represented by eight other genera
in the same country.



4 68



TUBE-BLADDERED GR O UP.
AFRICAN LOACHES, Family KNER



Two small loach-like fishes from the fresh waters of Tropical Africa, one of
which (Kneria conyolensis) is figured in the annexed illustration, alone represent a
family distinguished from the preceding by the absence of teeth on the pharyngeal
tones, and by the elongated air-bladder being undivided, barbels being wanting.
While tin- figured species is from the west coast, the other (K. spekei} inhabits
Central Africa.

THE CHARACINOID FISHES, Family ERYTHRINIVJE.

As an example of a very extensive family of fresh-water fishes, confined to
Tropical America and Africa south of the Sahara, we select an American form
known as the piraya (Serrasalmo piraya), since in our limited space it is quite
impossible to deal with any of the others. It may be mentioned, in the first place,




ANGOLA LOACH (liat. size).

that these fishes are commonly known as the Characinidcc, but as there is no
such genus as Ckaracinus, it is obvious that this term cannot stand, and we have
accordingly adopted another. According to Professor Cope's arrangement, these
fishes belong to the same sectional group as the carp tribe, from which they may
be distinguished by the brain-case not being produced between the orbits, and
likewise by the number of upper pharyngeal bones varying from four to one
instead of being always two ; a further point of difference occurring in the
structure of the upper jaw, which is formed in front by the premaxillfe, and at
the sides by the maxillae. Like the carps, the body is scaled and the head naked ;
but barbels are invariably wanting, and the jaws may be either toothless, or
furnished with a dentition of a very powerful type. In most cases there is a
small fatty fin behind the dorsal ; the air-bladder is always transversely divided
into halves, and there are no false gills. Unfortunately, there are no fossil forms
to aid in the explanation of the peculiar geographical distribution of the family,
which is very similar to that of the chromids ; but there can be little doubt that
the ancestral types originally inhabited the great land-mass of the Northern
Hemisphere, from whence they migrated southwards to their present isolated



CHAR A CINOIDS.



469



distributional areas. It is, however, not a little remarkable that whereas in their
migration to Africa they have been accompanied by members of the carp tribe,
in Tropical America they entirely take the place of that family. The numerous
genera, none of which are common to the two hemispheres, are ranged under
eleven groups or subfamilies, the majority of which are confined to either the one
or the other half of the distributional area, although a few have representatives
of both. As regards their habits, some of these fishes are strictly carnivorous,
while others are as exclusively vegetable-feeders.

The figured species belongs to the last subfamily, which includes four exclus-
ively American genera, represented by some forty species, and characterised by the
somewhat elongated dorsal fin, behind which is a small fatty fin ; by the gill-
membranes being free from the isthmus, and also by the distinct serration of the
middle line of the under surface of the body.

On account of their large size, two other genera of these fishes, which have
respectively received the names of Hydrocyon and Cynodon, must be mentioned;




THE PIRAYA (J nat. size).



the former being from Tropical Africa, and the latter from Brazil and the Guianas.
They grow to the length of 4 feet, and are highly predacious ; the subfamily to
which they belong being characterised by the presence of a short dorsal and anal
fin, the large conical teeth, the want of attachment between the gill-membranes
and the isthmus, and the approximation of the nostrils.

THE CYPRINODONTS, Family CYPRINODONTID^E.

The small fishes which, for want of an English title, we may designate
cyprinodonts, bring us to the first family of another sectional group termed the
Haplomi, which also includes the pikes. In addition to certain other structural
features of the skeleton, this group is characterised by the first four vertebrae being



TUBE-BLADDERED GROUP.



separate and of normal form ; while in the skull the parietal bones are separated
by the supraoccipital, all the opercular bones are present, and the pharyngeals are
distinct, the upper ones being directed forwards, and three or four in number. As
a family, the cyprinodonts are specially distinguished by the margin of the upper
jaw being constituted solely by the premaxillse, and the enlargement of the third
upper pharyngeal bone. Externally they may be readily distinguished from the
carps by the head being scaled as well as the body, and they have no barbels. Both
jaws are toothed, and the pharyngeals are also furnished with teeth, which are
heart-shaped. There is no fatty fin, and the dorsal is situated in the hinder half
of the body. The air-bladder is simple, and the false gills are wanting. Inhabiting
either fresh, brackish, or salt water, these fish are distributed over the south of
Europe, Africa, Asia, and America; some being purely carnivorous, while others
feed on the organic substances to be found in mud. Most of the forms are
viviparous ; and the males, which are much inferior in size to the females, and,
according to Dr. Gunther, probably the smallest living fishes, frequently have the
anal fin specially modified to aid in the reproductive process. As a rule, the fins are
relatively larger in the males than in the females, and there is likewise some
difference in the coloration of the two sexes. In a fossil state, remains of the

typical genus occur in the Miocene strata of the
Continent, which have also yielded others re-
ferred to an existing American genus ; while
the head of a species much larger than any now
living has been described from the Pliocene of
India, this specimen being figured in the accom-
panying illustration in order to show the scales
on the head so characteristic of the family.
Cyprinodonts are represented by about a score
of genera, which may be divided into two sub-
families, according to the nature of the food.
In the first of these, which includes the typical
genus Cyprinodon, and has a distribution co-
extensive with that of the family, all the forms
are carnivorous or insectivorous, and are char-
acterised by the firm union of the two branches

of the lower jaw in front, and likewise by the shortness, or slight convolution
of the intestines. On the other hand, in the second subfamily, which is exclusively
restricted to Tropical America, the species seek their food in mud, and have the
two branches of the lower jaw but loosely joined together, while the intestine is
highly convoluted. It is in this group that the sexual differences are most strongly
marked.

As an example of the family we take a remarkable genus
belonging to the first subfamily, represented by three species from
Tropical America, one of which (Anableps tetroptkalmus) is shown in the accom-
panying illustration. Having a broad and depressed head, with the region over the
eyes much raised, the elongate body compressed in front and depressed behind, a
protractile muzzle, and the cleft of the mouth horizontal and of moderate size, these




HEAD OF A FOSSIL CYPIUNODONT, WITH
ONE OF THE SCALES ENLARGED.



Double-Eyes.



BLIND FISH. 471

fish are specially characterised by the structure of the eye, which is quite unique
among vertebrates, and from which they derive their name. In each eye the
integuments are divided into an upper and a lower moiety by a dark-coloured
transverse band in the outer layer ; the pupil being likewise bisected in the same
plane by means of a lobe projecting from each side of the iris. The scales are of
small or moderate size ; the dorsal and anal fins short, the latter being placed in
advance of the line of the former, and in the male (which in this genus is larger
than the female) modified into a long, thick, scaly organ, with an aperture at the
end. These fishes are the largest existing members of the whole family, growing
nearly to a foot in length. They are abundant in North Brazil and the Guianas,
where they frequent mud-banks on the coast and in the estuaries of the larger







FEMALE AND MALE DOUBLE-EYE (J nat. size).

rivers ; many of them being often left stranded by the retiring tide, where they
progress on the slime by a series of leaps. After birth the young are carried about
by the female in a thin-skinned sac divided by a partition, until they are suffici-
ently advanced to take care of themselves. When swimming, these fishes frequently
go on the surface with the eye half in and half out of the water ; and it is in
accordance with this habit that the eyes are divided, the upper portion being able
to see in the air, while the lower is adapted for vision under water. That such is
really the case, is proved by the structure of the lens of the eye. In terrestrial
animals the lens is lenticular, that is to say, of the shape of two watch-glasses put
edge to edge ; whereas in ordinary fishes, which have to see in such a dense medium
as water, the lens is spherical. Now in the double-eye that portion of the organ of
vision which is above the level of the water has the lens lenticular, while in that
portion which is below the water the lens is spherical. In Brazil the flesh of these
fish forms an article of consumption.



472 TUBE-BLADDERED GROUP.

THE BLIND-FISH, Family AMBLYOPSID^E.

The celebrated blind-fish (Amblyopsis speloea) from the Mammoth Cave in
Kentucky, the Wyandotte Cave in Indiana, and the subterranean streams which
appear to connect the waters of the two, is generally regarded as the typical repre-
sentative of a family closely allied to the last. This fish, which does not exceed 5
inches in length, and breeds viviparously, closely resembles the genus Cypri/nodon
in that certain specimens (which have unnecessarily been separated as Typhlichtfi/ys)
lack the pelvic pair of fins. All traces of external eyes are wanting, and the skin is
totally devoid of colour. In order to enable the creature to find its way about in
the dark subterranean waters of the limestone rocks of the Central United States,
its head is provided with a large supply of organs of touch, arranged in a series of
transverse ridges on each side ; while its sense of hearing is also stated to be very
highly developed. Professor Cope writes that if these fish "be not alarmed, they
come to the surface to feed, and swim in full sight like white aquatic ghosts.
They are then easily taken by the hand or net, if perfect silence is preserved, for




KENTUCKY BLIND-FISH (liat. size).

they are unconscious of the presence of an enemy except through the medium of
hearing. This sense is, however, evidently very acute, for at any noise they turn
suddenly downwards and hide beneath stones, etc., on the bottom. They must
take much of their food near the surface, as the life of the depths is apparently
very sparse. This habit is rendered easy by the structure of the fish, for the
mouth is directed partly upwards, and the head is very flat above, thus allowing
the mouth to be at the surface. It thus takes food with less difficulty than other
surface-feeders, as the perch, where the mouth is terminal or even inferior ; for
these require a definite effort to elevate the mouth to the object floating on the
surface." Nearly allied to that variety of the blind-fish in which pelvic fins arc
absent is a small fish known as C/tologaster, in which small external eyes are retained,
and the body is coloured ; the front of the head being provided with a pair of horn-
like appendages. These small fish were first known from three examples laken in
the ditches of the South Carolina rice-fields, but a fourth specimen was captured in
a well in Tennessee in the year 1854. The retention of the eyes and their dark
colour indicates that these fishes have taken to a partially subterranean life more
recently than the blind-fish.



PIKE. 473

THE UMBRES, Family UMBRID^E.

A small fish from Austria-Hungary known as the umbre (Umbra krameri),
together with a second (U. liini}, locally distributed in the fresh waters of the
United States, indicate a family distinguished from the Cyprinodontidce by the
upper jaw-margin being formed in front by the premaxillary bones and by
the maxillary bones at the sides ; the base of the skull being of simple structure
in both families. Like the cyprinodonts, the umbres have the head and body
scaled, and no barbels to the mouth. There is no fatty fin, and the dorsal is
opposite the pel vies, or a little behind them, while the anal is short, and the
caudal rounded. The stomach merely forms an expansion of the intestine ;
the air-bladder is simple ; and the false gills are hidden and glandular. The
European species, which is known as the hunds-fisch in Germany, dwells in
marshes and muddy pools, where it buries itself in the mud at the bottom. As in
most cyprinodonts, the males are smaller and more slender than the females, scarcely
reaching a couple of inches in length, whereas the latter grow to 3 or 3^ inches.

THE PIKE, Family ESOGID^E.

Such a familiar fish as the pike (Esox lucius) scarcely requires much in the
way of description, but it is an important one as representing, with other members
of the same genus, a family by itself. Agreeing with the umbres in the structure




COMMON" I'lKK



of the jaws, pike may be distinguished externally by the absence of scales on the
head, and internally by the more complex structure of the base of the skull. The
body is covered with cycloid scales ; there are neither barbels nor a fatty fin ;
and the dorsal is situated in the caudal region of the vertebral column, in the
position of the fatty fin of the salmon tribe. The stomach has no blind appendage,
the false gills are glandular and concealed, and the gill-opening is unusually wide.
In the upper jaw sickle-shaped teeth are borne by the premaxilke, palatines, and
vomer, the maxilla being toothless, while the lower teeth are of variable shape.
The long narrow body terminates in a forked caudal fin ; and the long, broad, and
depressed snout has the lower jaw exceeding the upper in length. Confined to
the fresh waters of the temperate regions of the three northern continents, pike
may be considered a western rather than an eastern type, seeing that whereas the
common species has a range equivalent to that of the family, the whole of the
other six species are confined to the United States. In Europe the pike inhabits



474 TUBE-BLADDERED GROUP.

all the Russian rivers, with the exception of those of the Crimea and Trans-
caucasia, and is likewise found in Siberia. In Lapland it extends even beyond
the limits of the birch, while to the south it is common in the Venetian lagoons.
Growing very rapidly, the pike not uncommonly attains a length of 45 or 46
inches, with a weight of 35 or 36 Ibs. ; and although fishes of much larger
dimensions are on record, the accounts of these must be received with great
caution. It is pretty well ascertained that fish of 45 inches are not commonly
more than about fifteen years old, and the stories of examples living for a century,
or even more, appear to be legendary. Pike are among the most predaceous and
greedy of all fresh-water fish, nothing coming amiss to their voracious appetites,
since not only will they devour worms, leeches, frogs, trout, carp, and other fishes,
but they pull under the young, and often even the adults, of all kinds of water-
birds, and have no objection to an occasional water-vole. Their habit of lying
like a log in the water (from which trait they probably derive their name), as well
as the sudden rush they make after their prey, are well known to all ; and the
damage these fish do to trout-streams is almost incredible. Pike are also great
devourers of the smaller members of their own kind. Frequenting alike ponds, lakes,
and rivers, pike in Ireland spawn as early as February, but in England a month
or two later, while in some parts of the Continent the season lasts till May. Males,
which are inferior in size to their consorts, are said to be more numerous than the
latter ; and it is not uncommon for a female in spawning-time to be attended by
three or four members of the opposite sex, who crowd around her as she lies quiet
to deposit her eggs.

THE AFRICAN BEAKED FISH, Family MORMYRIDJE.

The very remarkable fish (M ormyrus petersi) shown in the upper figure of
the illustration on p. 475, is the best known African representative of a large
genus of fresh-water fishes confined to Africa, and constituting not only a family
but likewise a distinct section, to which Professor Cope applies the name of
Scyphophori. Having the narrow parietal bones of the skull distinct both from
one another and from the supraoccipital, these fishes are especially distinguished
by having each of the pterotics (which lie on each side of the parietals) large,
funnel-shaped, and enclosing a cavity expanding externally, and covered by a
lid-like plate of bone. The anterior vertebrae are simple and unmodified; ;ui<l
a subopercular bone is present in the gill-cover. Externally both the body
and tail are covered with scales, but the head is naked, and the muzzle has no
barbels. In the upper jaw the middle portion is formed by the united premaxilhe,
and the sides by the maxilla3 ; the gill-opening is reduced to a small slit; there
are no false gills; and the air-bladder is simple. A fatty fin is wanting; and
whereas in the typical genus all the other fins are well developed, in the allied
Gymnarchus (which is likewise exclusively African, and is sometimes regarded as
the representative of a distinct family), the caudal, anal, and pelvic fins are want-
ing, the tail tapering to a point, instead of terminating in a deeply forked fin.
The beaked fishes arc divided into groups according to flie length of the dorsal
fin and the form of the muzzle, the ligured species belonging to a group in which



FEA THER-BA CKS.



475



the dorsal fin is relatively short, scarcely exceeding the anal in length, while the
muzzle is long and bent down. From its nearest allies the species in question is
distinguished by the production of the extremity of the lower jaw into an
elongated, conical, dependent, fleshy appendage, nearly equal in length to half
the head. In colour the skin is dark brown, relieved by two lighter crossbands
between the dorsal and anal fins. Other species have the muzzle short and blunt ;
and whereas some grow to a length of between 3 and 4 feet, others are compara-
tively small fishes. No less than eleven species of this genus are found in the
Nile ; which, together with some of the West African rivers, is likewise the home
of the single representative of the genus Gymnarchus. In form the latter fish




PETERS' BEAKED FISH AND SLENDER PIKELET (J uat. size).

is eel-like ; its jaws being armed with a series of incisor-like teeth, and its length
reaching to upwards of 6 feet. Both genera are furnished with a pair of organs
lying on the two sides of the tail, which are stated to be transitional in
character between ordinary muscle and a true electric organ ; although, if this be
correct, it is difficult to conceive what can be the object or use of such a structure.
Each consists of an oblong capsule, divided by vertical partitions into a number of
chambers filled with a gelatinous substance. One of the species (M. oxyrhynchus)
from the Nile, is frequently depicted in the frescoes of the ancient Egyptians.

SECTION ISOSPONDYLI.i
THE FEATHER-BACKS, Family NOTOPTERID^.

According to the classification we are following, the whole of the remaining
members of the tube-bladdered fishes form a group denominated Isospondyli, and

1 On p. 333 the group Isospondyli is given as of equivalent rank with the Physostomi, of which, in the
scheme here followed, it should be only a section.



476



TUBE-BLADDERED GROUP.



characterised as follows. The parietal hones are completely separate; the
symplectic hone, which is wanting in the group last treated of, is present; tin;
anterior vertebrae are simple and unmodified, and both the upper and lower
pharyngeal bones are separate. The group includes the least specialised of all
the bony fishes, and those forming a transition to the ganoids. From the



Online LibraryRichard LydekkerThe new natural history (Volume 5) → online text (page 50 of 62)