HARVARD UNIVERSITY.

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ZO()L(Hil('VL COLLECTIONS

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FISH GALLERY

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INDIAN MUSEUM.

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Calcutta:

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1899
Pi ;ht annas.

GUIDE

TO THE

ZOOLOGICAL COLLECTIONS

EXHIBITED IN THE

FISH GALLERY

OF THE

INDIAN MUSEUM.

Calcutta:

Printed bt Order op the Trustees of the Indian Museum.

1899.

Price Eight annas.

6 IS
■ AH

OALCDTl'A : — BAl'TIST MISSION PUEtfS.

PREFACE.

The new Fish Gallery of the Indian Museum,
which in old times was the Library of the Geological
Survey, has been modelled on Dr. Giinther's well-
known Introduction to the Study 0/ Pishes, and to that
admirable work I have much pleasure in acknowledg-
ing my essential obligations.

In a country, like Eastern Bengal, where damp
and mould, as well as moth and rust, take hold of
everything in a way inconceivable by those whose
experience is confined to happier climates ; in a
country where even japan-varnished labels of
seasoned teak get mildewed : specimens can only
be safely exhibited as specimens, without any of
those attractive accessories that are needed to
transform them into studies of Nature. So that
the only attempt that has been made to lend veri-
similitude to the exhibits in this Gallery has been,
as far as possible, to hang the specimens by wires,
instead of fixing them on boards or stands, and to
paint them in their natural colours.

The limitations imposed by climate have led me
to seek to add interest to the Gallery in other direc-
tions; as, for instance, by exhibiting dissections,
maps of geographical distribution, and models of
characteristic deep-sea fishes.

These models are principally the work of the
Museum modeller, Panch Cowry Chatterjee. The
colouring of the specimens has been done by the
Museum draughtsman Abhoya Charn Chowdry.

A. Alcock, Major, /.M.S.,
Superintendent of the Indian Museum.

Calcutta, 1899.

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INDEX to the CONTENTS of the GALLERY.

rCase 1. Balanoglossus.

2-3. Tunicates.

4. Amphioxus (Lancelet).

5. Lampreys.

6-7. Varieties of Form among Fishes.

8-9. Topography, Scales and Skeleton of Fishes.

10. Heart, Breathing-organs and Abdominal
Viscera of Fishes.

11. Central Nervous System of Fishes.

12. Embryology and Development of Fishes.

13. Secondary Sexual characters of Fishes.

14. Some Bionomic Curiosities.
15-20. Characteristic Fishes of the Deep Sea.
21-22. Scheme of Classification of Fishes.
23-24. Subclass Dipnoi (Amphibious Fishes).
25-29. Ganoid Fishes.
30-32. Subclass Chondropterygii : Chimseras.

33-41. Subclass Chondropterygii : Sharks, Rays.

42-43. Anacanthine Bony Fishes,

43-59. Acanthopterygian Bony Fishes.

60-73. Physostomous Bony Fishes.

74-75. Plectognathous and Lophobranch Bony Fishes,

MAR 2 1900

A. GUIDE

TO THE

ZOOLOGICAL COLLECTIONS

EXHIBITED IN THE

FISH GALLERY OF THE INDIAN MUSEUM.

The Fishes are one of the five main divisions, or
Classes, of the Craniate Vertebrates, that is, of the
Vertebrates in which there is a brain, lodged in a skull,
or capsule of cartilage or bone.

With the Fishes proper it is usual to include the
Cyclostontata (typified by the Lampreys) which agree in
most respects with the Fishes, but differ from them and
from all other Craniate Vertebrates in having no true
jaws.

It has also been usual to include with the Fishes the
singular form Amphioxus, although, beyond the facts
that it lives in the sea and breathes through its mouth
and pharynx, it has no special resemblances with a
fish.

Amphioxus, besides many other peculiarities, is dis-
tinct from the Fishes and from all other Vertebrates in
having neither brain nor skull, and will here, therefore,
i

A Guide to the Zoological Collections

in accordance with the classification of Ray Lankester,
be regarded as an independent branch of the Vertebrate
stock.

It is convenient to exhibit in the Fish Gallery certain
more or less degraded marine animals in which the
vertebrate affinities are, at least in adult life, obscured.
These are the Ascidians [Tunicata) and Balanoglossus.
They have not the slightest external resemblance to
ordinary vertebrate animals, and in the case of the
worm-like Balanoglossus the vertebrate affinities are not
undisputed ; but the Tunicata are very reasonably con-
sidered to belong to the Vertebrate phylum principally
on the grounds (i) that their larva — though not usually
the adult — has a notochord or primitive foundation of a
backbone, (2) that at least the main mass of the nervous
system lies to the dorsal side of the level of the noto-
chord, and (3) that the front part of their digestive tube
is peculiarly modified for breathing.

It must be remembered that Balanoglossus and the
Ascidians are exhibited in the Fish Gallery simply for
convenience : they would be out of place in either of the
Galleries of Invertebrates, and they are not, from a
Museum point of view, important enough to have a
gallery to themselves among the Vertebrates ; although
from many other points of view they are among the
most important and most interesting of all animals.

BALANOGLOSSUS.

[Case 1.]

In external appearance, as in mode of life, the adult
Balanoglossus resembles certain marine worms. Its
larva in certain species, of which much enlarged figures
are shown in Case 1, resembles certain Echinoderm
larvae.

in the Fish Gallery of the Indian Museum.

It has been classed both with the Worms and near
the Echinoderms, but certain very suggestive peculiari-
ties of its structure have lately led the most advanced
zoologists to remove it to the Vertebrate phylum.

It is not possible to discuss all these peculiarities
here, but one of the chief of them, namely the essentially
vertebrate ground-plan of the breathing-mechanism, is
seen in the diagrams, specimens and model in Case i.
The general correspondence of the plan of the breathing
arrangements of Balanoglossus with those of certain
branchiate vertebrates is remarkable. This correspond-
ence would not of itself justify the inclusion of Balano-
glossus in the Vertebrate phylum, were it not that the
essentially vertebrate notochord and dorsal nerve-tube
are also represented, though obscurely and imperfectly,

in Balanoglossus.

The enlarged drawings and diagrams in Case i will
explain the structure of the animal.

No species of Balanoglossus has been found in these

seas.

TUNICATA.

Sea-Squirts.

[Cases 2-3.]

Owing to the fact that in the more familiar members

of the group the body wall forms a muscular mantle

and secretes a thick protective test, the Tunicates were

originally classed with the Mollusca.

But the knowledge that the larva of many Tunicates
has a notochord in the posterior part of its body, or tail,
and a dorsal nervous system (brain, etc.), formed on the
Vertebrate plan ; and that there are certain small free-
swimming Tunicates that keep the larval tail and brain ,
though somewhat changed, throughout life ; added to the

A Guide to the Zoological Collections

fact that breathing is effected in Tunicates, as in Am-
phioxus, by special modifications of the pharynx, has
now led to the advancement of the Tunicata to the
Vertebrate phylum.

In Ray Lankester's classification they stand as an
independent branch of that phylum, under the name
Urochorda, which expresses the fact that the embryonic
and larval notochord is confined to the tail.

The Tunicata, or Ascidians, or Sea-squirts, occur to
ordinary observation under two forms : namely, fixed
Tunicates that are found encrusting rocks, etc., in shallow
water near shore, and free-swimming Tunicates that
float at and near the surface of the open sea. Some of
the latter are very brightly phosphorescent, e.g., the
colony of Pyrosoma in Case 2.

In both forms the animal is usually encased in a
thick gelatinous or leathery tunic (hence the name
Tunicata), in which there are two openings : namely,
one at the fore-end, leading into the body, and corres-
ponding to the mouth of Vertebrate animals ; the other
either on the dorsal side, or at or near the after end, and
leading out of the body.

In the fixed Tunicates the test is either semi-trans-
parent or opaque, either gelatinous or leathery, and
often coloured, and has its two openings rather close
together: it often resembles a small leather bag —
hence the name ascidian, from do-Kos a leather bag, and

etSos form.

In the free-swimming Tunicates the test is trans-
parent and gelatinous, and has its two openings either
at or almost at the opposite ends of the body.

There is another form of free-swimming Tunicata
that, on account of its small size, needs careful searching
for with a drift-net. In this form, enlarged drawings

in the Fish Gallery of the Indian Museum. 5

of which are shown in Case 3, there is a tail for loco-
motion.

As the Ttmicata of these seas have never been named,
our exhibits are chiefly intended to illustrate some of
the more important anatomical modifications of this
most interesting group of animals.

The structure of the typical adult Ascidian is shown
in the series of drawings, dissections and enlarged
models in Cases 2 and 3.

The vertebrate affinities of the Ascidian larva are
represented by a series of enlarged drawings, chiefly
after Ray Lankester, in Case 3.

1. THE TTPICAL SIMPLE FIXED ASCIDIAN.

[Case 2.]

Nos. I and I in this Case are simple fixed Ascidians
preserved in spirit. Observe the form and orientation
of the body, the incurrent opening, or mouth, and the
excurrent or atrial opening, shown by labels.

Nos. II and III are simple fixed Ascidians in which
the whole of the right side of the test has been removed.
Observe the animal lying completely enveloped in its
mantle, which is the outer layer of the body wall ;
thus enveloped it appears to hang almost free within
the test. Notice also the siphons, or processes of the
mantle which open at the mouth and at the atrial
orifice.

Nos. IV. V. VI. are simple fixed Ascidians of which
the left side of the tunic has been removed, and more
or less of the left side of the mantle also. We now see
that beneath the mantle there is a space. This space
is the atrial or peribranchial cavity : it opens directly to
the exterior by the atrial or excurrent orifice of the test
only. The pointer in No. V shows the passage from the

A Guide to the Zoological Collections

peribranchial cavity, through the atrial orifice, to the
exterior.

In some of the dissections the whole of the left side
of the mantle, as well as of the tunic, has been removed,
to expose the whole of the large branchial sack. This
branchial sack is the pharynx : it almost fills the peri-
branchial or atrial cavity, and it opens directly to the
exterior by the mouth or incurrent orifice only as is
shown by the pointer in No. V : its walls, however, are
pierced with rows of pores, like a sieve, and through
these pores the branchial sack also communicates with
the peribranchial cavity. At its lower part, on the
dorsal side, (to the extreme right hand side of the ob-
server), it also leads into the alimentary canal: this
forms a double loop, the open end of which (anus) hangs
free in the peribranchial cavity at the bottom of the
atrial orifice.

We can now understand how the Ascidian feeds
and breathes. Seawater, carrying Oxygen and minute
particles of food, is drawn into the capacious pharynx
or branchial sack, at the mouth or incurrent orifice. The
food finds its way into the intestinal tract, and the undi-
gested waste ultimately escapes into the peribranchial
cavity near the atrial orifice. The water passes through
the pores in the wall of the pharynx, also into the peri-
branchial cavity, whence it escapes through the atrial
orifice, carrying with it, as it sweeps through the atrial
siphon, the waste from the intestine. As the water runs
through the pores in the very vascular wall of the
pharynx, it gives up its oxygen to the blood.

The other organs of the Ascidian can be seen in the
dissections and in the explanatory drawing beside

them.

It is necessary to explain how the particles of food

in the Fish Gallery of the Indian Museum. 7

that enter the branchial sack with the water of respira-
tion find their way into the gullet.

The mechanism by which this is effected is shown in
dissection No. VII. Case 2.

In this dissection the right wall of both test and
mantle have been cut away and the right wall of the
branchial sack split open longitudinally and flapped
back, so as to show the whole interior of the branchial
sack.

We can now see, (1) running along the ventral wall
of the sack (right hand side of the observer) a groove
called the endostyle, and (2) running along the dorsal
wall of the sack (left hand side of the observer) a pro-
jecting fold called the dorsal lamina.

Where the dorsal lamina ends, the opening of the
gullet (marked by a silver wire) is seen.

The particles of food, washed into the branchial sack,
are caught by the secretion of the endostyle and are
carried forwards along the endostyle to the dorsal
lamina. They then pass backwards, matted together,
along the dorsal lamina to the opening of the gullet.

The enlarged and coloured clay models in Case 3,
which have been made from the dissections, show
plainly the organs of respiration and digestion of the
typical Ascidian and their relations to the mantle and
test.

The dissections enable us to realize that the breath-
ing organ of the Ascidians is on the same plan as that
of Amphioxus; but the other vertebrate affinities of the
Ascidians can only be illustrated here by drawings.
These, which are exhibited in Case 3, show that the
larva of the kind of Ascidian that we are considering
has a considerable resemblance to a frog's tadpole. It
has a head and a tail, In the tail there is a notochord,

8 A Guide to the Zoological Collections

corresponding, so far as it goes, with that of Amphioxus
and Vertebrate embryos, and — dorsal to the notochord —
a nerve tube with the same general correspondences.
In the head there is a hollow swelling of the nerve-
tube having a fundamental identity with the brain of
higher Vertebrates.

Some of the steps by which the free-swimming larval
" Ascidian tadpole " changes into the degenerate fixed
Ascidian are shown in a series of enlarged drawings
after Ray Lankester.

2. LARVACEA .
[Case 2.]

As has been already mentioned, there are certain
very small Tunicates that swim freely through the open
seas, and that keep the tail, though not quite in the
tadpole form, throughout life.

Enlarged drawings and models of some of these are
shown in Case 3. They have no peribranchial cavity,
and the branchial sack therefore opens directly to the
exterior, — by two pores or gill-slits.

3. COMPOUND ASCIDIACEA.

[Case 2.]
Certain Ascidians that resemble in their general
anatomy the form shown in our dissections, are able to
form colonies by budding. They are represented here
chiefly by glass models. Some of these compound
Ascidians, as the Pyrosoma in Case 2, are free-swim-
ming inhabitants of the open seas.

4. THALIACEA.

[Case 2.]
Salpay of which glass models and spirit specimens,
and Thalia, of which stained glycerine specimens are

in the Fish Gallery of the Indian Museum. 9

exhibited, are types of free-swimming Tunicates that
differ considerably from the simple fixed Ascidian. In
Salpa the branchial sack and the peribranchial cavity
form one continuous space, and the branchial and atrial
openings are at opposite ends of the body. This is a
special modification for locomotion, the animal being
propelled forwards by the forcible expulsion, from the
atrial opening, of the water that has been drawn into the
peribranchial cavity : this is effected by the contraction
of muscular bands in the mantle. Thalia moves through
the water in the same way.

AMPHIOXUS.
Lancelets.
[Case 4.]

This curious little fish, of which spirit specimens are
shown in Case 4, is so small that its structure can only
be illustrated in a Museum by enlarged drawings and
diagrams.

No. 1 is a drawing of an Amphioxus enlarged 18
times, No. 2 is a much more enlarged diagrammatic
drawing of a cross-cut through the fore-end of an
Amphioxus. No. 3 represents the mode of life of
Amphioxus.

The species are of world-wide distribution in tropical
and temperate seas, one species being common enough
in shallow water along the Madras coast. They pre-
fer sandy bottoms into which they can burrow, leaving
only the fore-end of the body exposed. In this position
they breathe and feed almost exactly in the manner of
the Ascidians, drawing through the mouth, into a
capacious pharynx, currents of water that contain
oxygen and minute particles of food. The water passes
through slits in the wall of the pharynx into a special
2

io A Guide to the Zoological Collections

peribranchial or atrial cavity, whence it is discharged
by a special opening, situated in the middle line some
way in front of the anus, known as the atrial opening
or atriopore ; while the food is caught and carried, by
structures corresponding with the endostyle and dorsal
lamina of the Tunicates, into the alimentary canal,
whence the undigested waste escapes at the anus.

The atriopore is indicated by a pointer in one of the
specimens, the anus by a red circle.

Drawing No. i shows (i) the long smooth compressed
lancet-like body tapering to a sharp point at both ends
(whence the name Amplii-oxus) and showing no distinc-
tion whatever of head, trunk, and tail : (2) the long fold
of skin, or dorsal fin, running from the right side of the
mouth all along the middle line of the back, and its
gelatinous fin-rays ; the short fold, or ventral fin, run-
ning between the atriopore and the anus, and its fin-
rays ; and the caudal fold or fin, connecting the other
two round the end of the tail : (3) the V-shaped muscle-
segments extending in a chain from one end of the body
to the other, but leaving exposed, at either end, the tip
of the (4) notochord. [This, which is seen in section in
Drawing No. 2, is a solid elastic rod of semi-cartilagi-
nous consistence that extends all along the middle of
the back, and is all that Amphioxus possesses in the
way of a true skeleton] : (5) the mouth, at the fore-end
of the body, encircled by small stiff oral tentacles: (6)
the anus, which lies a little to the left of the middle line,
near the after end : (7) the atriopore, some little way in
front of the anus: (8) the series of reproductive organs,
or gonads, showing through the semi-transparent body-
wall.

Drawing No. 2 is meant to show specially : — (1)
the position and form of the notochord : (2) the posi-

in the Fish Gallery of the Indian Museum. 1 1

tion and form of the central nervous system : (3) the
pharynx and gill-clefts, with the endostyle and hypo-
pharvngeal groove : (4) the peribranchial or atrial
chamber (coloured pink) into which the water is swept
after it has been used in breathing : (5) the metapleural
folds, or hollow folds of skin that run on either side of
the body, right and left, from the mouth to the region
of the atriopore.

As previously stated, Amphioxus has no place among
the Fishes, and is now generally regarded as the
representative of a separate branch of the Chordate
phylum.

It differs from all the true vertebrates (1) in having
no brain or skull of any sort, and hence no true paired
eyes : (2) in the form of the liver, which persists as a
hollow pouch of the gut ; and in the absence of a pan-
creas ; (3) in having no true heart and no red blood
corpuscles ; (4) in the curious primitive form of the renal
organs, which recall the Annelid type ; (5) in the large
number of paired reproductive glands ; (6) in the curious
asymmetry, not merely . of the body, but also of the
muscles, nerve-trunks, olfactory organ, and anus.

It further differs from all true vertebrates except the
Lampreys in having no true jaws and no branchial
bars. And it further differs from all Fishes in having
a vast number of gill-slits.

CYCLOSTOMA.
Lampreys and Hag-fishes.
[Case 5.]

The Cyclostoma have usually been included among
the Fishes, but they differ from all true fishes in having
no branchial bars and no jaws, in this last respect

12 A Guide to the Zoological Collections

differing also from all vertebrates above the level of
Amphioxus.

The specimens and dissections of Petromyzon (Lam-
prey) exhibited in Case 5 show that the body is worm-
like, without paired fins, but with unpaired dorsal and
caudal fins supported by fin-rays, and without scales.

The mouth is a funnel, the walls of which are studded
with strong conical horny teeth, and, with the piston-
like tongue, forms an adhesive sucker. It is supported
by plates of cartilage, and is surrounded by fleshy lips.

The gills are enclosed in pouches, which lie in a row
on either side of the gullet. The pouches — one of
which has been cut open to show the gill-leaves — open
on one side, indirectly, into the gullet, and on the other
side directly to the exterior : they are supported by a
cartilaginous basket-work, which has been dissected off
in the exhibited preparation.

Immediately behind the gills is seen the heart, which
is of the ordinary fish type described further on. The
branchial artery is seen running from the heart between
the two rows of gill-pouches, and sends a branch to
each pouch.

The skeleton is very imperfect. Instead of a back-
bone there is a simple elastic rod-like notochord : this
is enclosed in a sheath, from which a series of cartila-
ginous arches arise to cover in the spinal cord (dorsal
nerve-tube) that lies immediately above the notochord.
The relative positions of these organs are well seen in the
cross-slice of the body of a Lamprey in Case 5. The
skull is a mere capsule of cartilage.

The eyes are small and are more or less embedded in
the skin. The nostril is a single pore placed in the
middle line of the head.

The Lampreys are found in rivers and shallow seas

in the Fish Gallery of the Indian Museum. 13

in temperate regions. They are predaceous, attaching
themselves to their living prey— a fish — by their adhe-
sive mouth, in the manner of a parasite.

The Hag-fishes are found in the seas of the colder
parts of temperate regions : they feed in much the same
way as the Lampreys, but often bore their way right
into the abdominal cavity of their living prey.

FISHES.
[Cases 6-64.]

The Fishes constitute one of the five main divisions,
or Classes, of the Craniate Vertebrates.

The Vertebrata are defined, in the most general way,
as Coelomate § Metazoa t possessed of the three follow-
ing characters : —

(1) A dorsal axial skeleton, which, in a few of the
lowest and in the earliest embryonic stages of the
higher Vertebrata, consists of a simple unsegmented
soft rod (notochord), but which in the great majority of
Vertebrata is gradually replaced, in the course of
development, by a firmly-jointed chain of bones (verte-
brae), known as the vertebral column, or backbone.

(2) A central nervous system lying to the dorsal side
of the axial skeleton (notochord, backbone) in special
processes of which it is usually enclosed. This dorsal
nervous system is at first tubular.

§ Metazoa are animals that consist of a multitude of reciprocally-interde-
pendent cells of various form function and arrangement : in contradistinc-
tion from Protozoa, or animals that consist either of one single independent
cell, or of a small mass of cells quite similar to one another in form and
function, and independent of one another.

t Coelomate Metazoa are those that possess a body-cavity, or coelom, in
which the digestive tube is suspended and the viscera are lodged : in contra-
distinction from Coelenterate Metazoa, in which the only hollow of the body
is the digestive cavity.

14 A Guide to the Zoological Collections

(3) A digestive tube of which the fore end is in part
modified for breathing purposes.

In addition, almost all Vertebrata are bilaterally
symmetrical, and most have a heart, placed towards
the ventral side of the body, and a closed system of
vessels in which red blood circulates : also in a great
majority there are two pairs of limbs suspended from
the vertebral column.

The Vertebrata are arranged by Professor Ray
Lankester in four branches, namely, Craniata, Ccphalo-
chorda (Amphioxus), Urochorda (Tunicata), and Hemi-
chorda (Balanoglossus).

The three last have been already treated, so that we
are now concerned only with the Craniata.

The Craniate Vertebrates are divided by the same
authority into two " Grades," namely, Cyclostoma or
jawless Craniates, and Gnathostoma or Craniates with
jaws and with (persistent or transient) branchial bars.
The Cyclostomes have just been spoken of, so that we
now are left with the Gnathostome Craniates alone.
These are grouped in five great Classes : —
Fishes, Amphibia, Reptiles, Birds and Mammals.
All the members of these five classes possess jaws
and, at some time of life, a series of bars, known as
branchial arches, suspended behind the jaws.

In the Reptiles, Birds and Mammals, the branchial
arches, except the first which becomes the hyoid bone,
disappear as independent structures early in embryonic
life, as they do in adult life in many Amphibia : but in
the Fishes, as well as in most Amphibia during larval
life at least, they are important structures, most of them
bearing gills for breathing air dissolved in water.

The Fishes and Amphibia are thus most closely
related to one another, and they further agree with one

in the Fish Gallery of the Indian Museum. 15

another, and differ from the three higher Classes, in
being without an amnion and allantois during embryo-
nic life. [An amnion is a special envelope formed for
the protection of the growing embryo. An allantois is
a special outgrowth of the hinder part of the gut of the
embryo, carrying with it blood-vessels, for the primary
purpose of respiration.]

Fishes however differ from Amphibia in the form of
the limbs, which in Fishes — when they are present — are
fins, while in Amphibia — when present — they are seg-
mented limbs ending in digits. In Fishes again the
respiration is more completely aquatic ; for though there
are a few fresh-water fishes that have lungs in addition
to gills, the immense majority of fishes breathe,
throughout life, exclusively by gills : and though most
Amphibia when they leave the egg breathe entirely by
gills, and though some Amphibia keep their gills
throughout life, yet a majority of Amphibia, in the adult
stage, completely lose their gills, and even those that
do not lose them have lungs in addition.

The Fishes, like the Amphibia and Reptiles, are
"cold-blooded;" that is to say, there is no nervous
mechanism for controlling the temperature of the body,
which therefore rises and falls with the temperature of
the environment.

The form of the body among Fishes is generally
that of a spindle, a form that is admirably adapted for
cleaving a way through a resistant medium like water.
This form, which is almost universal among active-
swimming species, has necessarily become profoundly
modified, in various ways, to suit various other modes
of life.

1 6 A Guide to the Zoological Collections

[A considerable series of preparations in Cases 6, 7, 8,
is meant to illustrate some of the most striking of these
modifications of form.]

For instance, in the Flat-fishes (see Pleuronectes)
which live and feed on the bottom, and lie on one side,
the body is strongly compressed and leaf-like, and the
eye of the underside has travelled round to the upper-
side, so that both eyes are on one side of the head.

In the Pomfret (see Stromateus) which, however, is a
fish that swims free, the body is almost as much com-
pressed as it is in many Flat-fishes.

In the Skates and Rays, (see Trygon) which gener-
ally live and feed on the bottom, the head and trunk
are depressed, — giving the body a disk-like form, and
the tail is a lash-like organ of defence.

In the Pediculati or Frog-fishes (see HalieutcBa and
Lophius) which also, usually, live on the bottom, the head
and body are enormously enlarged and are depressed
like a disk.

In the Eels (see Muraena) which are able to creep
under rocks and into holes and crevices, the body is
long cylindrical and snake-like.

In the Hairtails (see Trichiurus) the body is strap-
shaped and the tail is long tapering and lash-like.

In the Pipe-fishes (see Gastrotoceus) many of which live
in brackish water among weeds, the body is long, thin
and rigid, very much like a stalk or a blade of grass.

In the Sea-horses (see Hippocampus) the body has a
most singular resemblance to the conventional knight
of the chess-board.

In the Box-fishes (see Ostracion) the form of the body
is coffer-like.

In the Hammerhead Sharks (see Zygccna) the name
well expresses the curious abnormality of form.

in the Fish Gallery of the Indian Museum. 1 7

The Topography of the Body of a typical fish may-
be studied from the lettered preparation of a Sea-perch
(Lates calcarifer : Bekti) in Case 8.

The head is delimited from the trunk by the gill-
opening, the slit by which the water that has been used
in breathing ultimately escapes from the pharynx. In
the head we see (1) a wide mouth, (2) eyes without true
eyelids, and (3) nostrils, which do not, however, open
into the pharynx. There are no external signs of an
ear, because the organ of hearing in fishes is lodged
within the bones of the head.

The trunk is delimited from the tail by the vent : the
tail is the tapering part behind the vent.

In the middle line of the back is a fold of skin sup-
ported by rays : this is the dorsal fin, which may either
be entire or be cut into two or three pieces. In the
middle line of the under surface of the tail, occupying
part or all of the space behind the vent is a similar fold
of skin supported by rays : this is the anal fin. Extend-
ing vertically round the tail is a third similar fold of
skin supported by rays : this is the caudal fin, which is
very often forked. These three series of fins are known
as the vertical or unpaired fins: the manner in which
their rays are loosely articulated with the skeleton may
be studied in the labelled skeleton of the Cod-fish in
Case 9.

Besides these vertical unpaired fins, there are, in the
specimen we are examining, on the trunk, two symmet-
rically paired fins. The front pair, placed immediately
behind the gill-opening on either side, are the pectoral
fins : they correspond with the fore-limbs of higher
Vertebrates. The hind pair, which stand out on either
side of the belly behind the level of the pectorals, are
the ventral fins : they correspond with the hind limbs
of higher Vertebrates.
3

iS A Guide to the Zoological Collections

The pectoral fins may be altogether absent, as they are in some eels.
However they are far more constant than the ventrals, and although the
height at which they stand varies a little, their position is always constant
immediately behind the gill-opening. Their extreme of development is
found in the Flying-fishes. In the Paradise- fishes (Polynemus : " Topsi")
some of their rays are of prodigious length and form organs of touch. The
same thing is seen in Bathypterois Guentheri a fish that lives in great depths
of the ocean where little sunlight penetrates and where therefore eyes, being
probably useless, are liable to degenerate. Degeneration of the eyes lias
occurred in Bathypterois and, in compensation, some of the rays of the
pectoral fins have become long " feelers," by means of which the animal
probably feels its way in the perpetual gloom, in much the same way as a
blind man feels his way with a stick.

The ventral fins are far more variable in position than]the^ pectorals and
are usually smaller. In some fishes, for instance in all eels, they are
altogether absent. In others, as in the whole Order of Physostomes they
are, when present, placed far back on the belly. In others, as in the Perch
we are considering, they are placed far forwards under, or just behind, the
pectorals. In others, as in the Cod-fishes they are placed on the throat, well
in front of the pectorals.

Although the paired fins of Fishes correspond with
the limbs of higher Vertebrates, and although they are
of some use as motors, they are not the principal means
of locomotion ; for locomotion in most fishes is effected
by the pliant muscular tail and the caudal fin.

In most fishes the SKIN, as in the specimen of Sea-
perch that we are examining, is covered with scales,
which are often imbricate. Scales are of four principal
kinds, namely : — (i) Cycloid scales, which are thin horny
plates with a thin smooth edge; (2) Ctenoid scales,
which are thicker horny plates with sharp spines on the
hinder edge and often also on the exposed surface; (3)
Ganoid scales, which are hard bony plates covered with
a layer of still harder enamel : they do not overlap, but

in the Fish Gallery of the Indian Museum. 19

often interlock with one another ; (4) Placoid scales,
which are either bony granules or tooth-like bony-
plates with a covering of enamel : placoid scales are,
in fact, often not different, either in form or composi-
tion, from the teeth of the fishes that possess them.

In most fishes (see the labelled Sea-perch in Case 8)
a row of scales along either side of the body is speci-
ally modified to form what is known as the lateral line.
This is a subcutaneous groove that usually extends from
the back of the head to the tail, and the scales that
cover it are channeled and perforated and are specially
provided with nerve-endings, so that the lateral line is
an organ of sense.

A series of specimens of the various sorts of scales is
to be found in Case 7.

The scales of fishes are usually imbedded in distinct pockets of the skin,
and are protected (as also is the skin of those fishes that have no scales) by
a copious layer of slime, or mucus, secreted by small cutaneous glands.

The integument of Fishes is almost always coloured. The colours fade
both in dried and spirit specimens, but in this Gallery an attempt has been
made, as far as possible, to represent the natural colours by painting.

The tints are commonly dull with a metallic sheen, but many marine
species are most gorgeously coloured.

Fishes that live on sandy and shingly bottoms are often speclded and
marbled in various shades of yellow and brown on the upper surface (or, in
the case of Flat fishes, on the upper side) ; while those that haunt reefs
encrusted with a variety of sea-weeds and zoophytes are often most wonder-
fully mottled, or else have the skin decorated with frond-like tags and tassels
and fringes. By thus harmonizing with the colour and form of surrounding
objects they escape the notice of their enemies and avoid scaring their prey.

Moreover, many fishes can, within certain limits, temporarily change colour
to suit changes in their surroundings : this is brought about by varying the
amount of contraction and expansion of the special cells — known as chro-
matophors, or colour-carriers — in which the colouring-matter is contained.
For instance a fish may, as in the case of several species of Platycephalic
be dependent for its colouration on two pigments — yellow and dark
brown, which in ordinary circumstances are arranged in bands across the
body. If, however, the fish be resting on a dark surface, the yellow cells

2o A Guide to the Zoological Collections

may contract and the dark cells expand to such an extent that the prevailing
colour of the fish may be dark brown ; but if, on the other hand, it be resting
on a hght surface, the dark cells may contract and the yellow cells expand
until the fish appears almost yellow.

Or, as in the case of Batistes maculatus, the ordinary colouration is blue-
black with light blue spots, somewhat resembling that of certain unpleasant
sea-urchins of the reefs among which this fish is found. If, however, the
fish be resting against a very dark surface (as, for instance, a piece of' dis-
coloured drift-wood) the light-blue cells may contract until they are almost
invisible.

One of the most « chameleonic » fishes of Indian Seas is Pterois miles
(Case 7) which, when creeping among the encrusted rocks of coral reefs,
presents almost every intermingled shade of red and brown, but which, when'
forced by pursuit into the blue water of the open lagoon, can become'almost
blue.

In connexion with the integument it must be mentioned that in some fishes
its mucous secretion may be poisonous. In Indian waters there are many
such •' poisonous " fishes. The commonest are the Sting-rays, which by
means of a huge barbed spike on the dorsal surface of the base of the tail
can inflict a poisoned wound that may even prove fatal.

Plotosus anguillaris is a Siluroid fish that with its large barbed dorsal
spine-and perhaps also with the similar spine of the pectoral fins-inflicts
a wound as painful as the sting of a hornet.

In neither of these cases have any special poison-glands been discovered,
so that we must suppose that the secretion of the skin in the neighbourhood
of the spines is poisonous. In Synanceia verrucosa (Case 53), however, each
spine of the dorsal fin supports a cutaneous poison-bag, the spine' itself
being grooved to carry the poison into the puncture made by its sharp
point. F

In connexion with the integument, too.it must be mentioned that some
fishes-especially among those species that either live habitually at ^reat
depths to which no sunlight penetrates, or that live at a considerable cTepth
of the open sea and only come to the surface at night-have luminous
organs imbedded in the skin. Specimens of several such species, that inhabit
the Indian Seas, are shown in the gallery.

The Skeleton among Fishes occurs under two prin-
cipal types of form,— the BONY skeleton characteristic
of the large Order of Bony Fishes, and the CARTILAGIN-

in the Fish Gallery of the Indian Museum. 2 1

OUS skeleton characteristic of the Sharks and Rays.
Although there are also several modifications of these
two types, some of which are more or less intermediate
between them, it is here sufficient to consider these two
common types, as illustrated by the labelled skeletons
in Case 9 of the Cod-fish and Dog-fish.

The skeleton of the Cod is of the well-ossified or bony
type, and as all the bones are named, the present des-
cription refers only to its general composition.

It consists of two portions, namely : (1) the axial skele-
ton including the jaws, hyoid bone, branchial arches
proper, and ribs, and (2) the skeleton of the appendages.

The Axial Skeleton consists of (1) the skull, or brain-
case, and (2) the backbone, which replaces the notochord,
and in which the remains of the notochord are imbedded.

The skull includes (1) the segmented brain-case, or
cranium, (2) the bones that enclose the organs of the
special senses — nose, eye, and internal ear, (3) the bones
of the palate and jaws, and (4) the bones that support and
cover the gills or breathing-organs. Observe (1) that
the cranium forms much the smaller part, and that the
bones of the mouth and breathing-organs form much
the larger part, of the skull ; (2) that the bones of the
mouth and gill-cover are slung from the skull, on either
side, by a large hyomandibular ; (3) that the five pairs of
branchial -arches (of which only the first four bear gills)
are slung from the base of the skull.

The backbone consists of a chain of rather simple
vertebrae, to some of which, behind the first, a pair of
ribs are attached. Those in front that bear ribs are
known as abdominal vertebra, those behind that have no-
ribs are known as caudal vertebra. Observe that the
backbone appears to end abruptly at two large plates of
bone of nearly equal size that support the caudal fin,,
forming what is known as a homocercal tail.

22 A Guide to the Zoological Collections

The form and composition of the individual vertebras
can be learnt from the labelled specimens of abdominal
and caudal vertebrae mounted alongside the skeleton.
Each of these consists of an hour-glass-shaped body or
centrum, hollowed at both ends. From the dorsal sur-
face of the body two neural plates arch up and meet
above the spinal cord (which they encircle), to form a
neural spine.

From the ventral surface, also, of the body of the
caudal vertebra a pair of haemal plates, almost exactly
like the neural plates, descend and meet to form a
haemal spine : in the haemal arch, or space between the
haemal plates, the main artery of the body runs.

In the case of the abdominal vertebra the haemal
arch is replaced by a pair of ribs.

Besides the neural and haemal processes and spines
there are articular facets by means of which (i) the
neural processes of the different vertebras are articu-
lated together, and (2) the ribs, when present, are arti-
culated with the vertebra that carries them.

The Appendicular Skeleton relates to the paired fins.
The pectoral fins are suspended from the head by means
of a very complicated shoulder-girdle, from which the
fin-rays radiate without the intervention of any bones
corresponding to an arm. The ventral fin-rays are
attached in the same way to a pair of simple pubic
bones.

[The rays of the unpaired fins are loosely connected
with the neural or haemal spines of the vertebras by a
series of interspinous bones.]

The skeleton of the Dog-fish represents the cartila-
ginous type.

in the Fish Gallery of the Indian Museum. 23

The skull is an unsegmented cartilaginous capsule, of
which the roof is often in places incomplete, and to it
the cartilages that protect the organs of special sense
are firmly attached, — the snout, or parts enclosing the
organ of smell, being often enormously developed. The
jaws, which are much less complicated than they are in
the bony fishes,. and the hyoid bone, are also of carti-
lage ; as also are the branchial arches proper, which
further differ from those of the bony fishes (1) in being
suspended from the anterior part of the " backbone,"
(2) in having cartilaginous branchial rays for the support
of the gill-chambers, and (3) in not having a gill-cover.

The backbone consists of a chain of cartilaginous
vertebrae and is prolonged into the upper lobe of the
caudal fin, forming a hcterocercal tail.

The appendicular skeleton consists of two cartilagin-
ous arches — one for the pectoral fins the other for the
ventral fins — to which plates of cartilage are attached,
and from these the cartilaginous fin-rays radiate.

The typical cartilaginous skeleton, above briefly described is not found,
unmodified, in all the members of the large Order (of Sharks and Rays) to
which the Dog-fish belongs. For instance, there are Sharks in which the
vertebrae, and even some of the bones of the head, are more or less calcified ;
there are Rays in which the vertebra? are partly ossified ; and there is one
small section of the Order in which rudimentary gill-covers are present.

The essential difference between the skull of a Shark and that of any of the
higher Vertebrates is, that in the latter the primitive skull is not only ossified,
but also becomes roofed-in by large bones (dermal bones) formed in the original
integumentary covering of the skull. In the Shark the primitive skull remains
unossified and unconnected with any ossifications in its integumentary cover-
ing.

It has been stated that the rays of the paired fins of
Fishes are not connected with any stem representing
the axis of the limb of higher Vertebrates. An excep-
tion to this statement must now be made.

24 A Guide to the Zoological Collections

In the small but highly interesting Sub-class of
Dipnoi (Case 23 & 24) the skeleton of the paired fins is
comparable to that of the limbs of higher Vertebrates ;
for it consists of a long segmented cartilaginous rod to
which the rays, when present, are articulated. The
dissection of the fore-limb of Ccratodus in Case 25 dis-
plays this.

The Digestive System of Fishes is illustrated by two
dissections in Case 10, of a Sea-perch {Pristipoma) and
of a Ray {Trygon) in which the abdominal cavity has
been completely laid open and all the viscera labelled,
with the exception of the liver, which has been removed
for the sake of clearness.

In the Sea-perch {Pristipoma) observe the large
mouth, the small tongue, the capacious pharynx with
four wide gill-slits on either side, the short gullet, the
Y-shaped stomach, the pyloric appendages, the single
loop of the small gut, and the straight large gut open-
ing at the vent. [The pyloric appendages are narrow
pouches that surround the intestine at its junction with
the stomach. Their microscopic structure does not
differ essentially from that of the neighbouring intes-
tine, into which they open].

In the Ray {Trygon) observe the U-shaped stomach,
the absence of pyloric appendages, and the very short
and wide intestine, which has been cut open to show how
its absorptive surface is increased by the broad spiral
pleating of its mucous membrane, known as the spiral
valve. Observe that the intestine opens into a pouch
common to it and the urinary and generative organs,
called the cloaca.

in the Fish Gallery of the Indian Museum. 25

The pancreas and spleen are left in their natural
position, but the liver, which is a large oily organ that
fills a large part of the abdominal cavity, has been
removed.

The mouth of Fishes is generally large, and teeth are generally present
not only in the jaws, but often also on several bones of the palate, and even
on the tongue and on parts of the branchial arches. It would almost need a
special gallery to exhibit the various forms of teeth that are found among
Fishes : they all, however, agree in being impermanent structures that are
shed and replaced throughout the life of the animal, and in being more
usually fixed to the bone than sunk in sockets ; and although in certain Fishes
that feed on hard substances such as mollusks and living coral they are
adapted for crushing, they are never organs of mastication, but are merely
used for prehension, — for the majority of fishes are predaceous and bolt their
prey whole.

The gullet is short and wide, and the stomach is large and capable of
enormous distension, especially among the highly predaceous deep-sea fishes,
some of which can swallow prey actually larger than themselves.

The general nature of the BREATHING-ORGANS and
Heart in Fishes is illustrated by dissections of a Ruhu
[Labeo) and of a Sting-ray (Trygon) in Case 10, in which
the pericardial cavity that contains the heart has been
opened, and the main arteries and the gills have also
been laid bare.

In both these fishes the breathing-organs, or gills,
consist of rows of leaf-like vascular folds of mucous
membrane, attached to the branchial arches like the
barbs of a feather, in which the blood gets rid of its
gaseous impurities and absorbs Oxygen from the sur-
rounding water.

In both, also, the heart lies immediately behind the
gills and consists, from behind forwards, of the following
parts: (1) a thin walled venous sinus, into which the
4

26 A Guide to the Zoological Collections

&*

great veins of the body open ; (2) a thin -wal led auricle
that receives the blood — valves preventing regurgita-
tion— from the venous sinus ; (3) a thick-walled muscular
ventricle, which receives the blood — valves intervening —
from the auricle and propels it to the gills.

The Gills of the Sting-ray exemplify the type of the
Sub-class Elasmobranchii. They are contained in sepa-
rate gill-pouches, of which there are five pairs, arranged
in two rows, one row on either side of the pharynx.
Each gill-pouch has a separate opening, not only into
the pharynx but also to the exterior. The gill-pouches
are supported by the hyoid and branchial arches and
their "branchial rays" before mentioned. Each pouch
contains two half-gills, except the last, which contains
only one half -gill. Besides the five pair of gill-pouches,
there is a pair of spiracles which open into the pharynx,
and also to the exterior just behind the eyes : they do
not bear functional gills, but they are of use in respira-
tion by admitting water into the pharynx: they are
homologous with gill-clefts, being in fact the pair of
clefts between the jaws and the hyoid bone, that is to
say between the first two primitive branchial arches.

In the Heart of the Sting-ray (Elasmobranch type) the
ventricle ends in a muscular, pulsatile, many-valved
arterial bulb, or arterial cone, from which a single large
branchial artery issues and runs forward between the
two rows of gill- pouches, giving off a branch to each
pouch. These branches of the branchial artery break
up and ramify in the gills for the purification of the
blood. The purified blood is collected by a correspond-
ing series of arteries, which finally unite to form a
single large blood-vessel— the dorsal aorta — that runs

in the Fish Gallery of the Indian Museum. 27

beneath the backbone and supplies the whole body with
pure oxygenated blood.

The Gills of the Ruhu exemplify the type of the Sub-
class Teleostei. There are four pairs of them, attached
to the convexities of the first four pairs of branchial
arches, and they lie in a gill-chamber on either side of
the pharynx. Each gill-chamber is protected by a
gill-cover, and opens into the pharynx by four wide
branchial clefts, but opens to the exterior by a single
gill-slit. Special processes known as gill-rakers are
generally present along the concavities of the branchial
arches — especially of the first — to strain the water as
it passes from the pharynx into the gill-chamber.

In the Heart of the Ruhu (Teleostean type) the vent-
ricle gives of a single branchial artery, which has the
same course and distribution as that of the Sting-ray,
but has no muscular pulsatile arterial cone at its base
but only a fibrous thickening known as the aortic bulb.

The mechanism of breathing in Fishes is as follows.
Water containing oxygen in solution is drawn into the
pharynx either through the mouth alone, or, when
spiracles are present, through the spiracles also. The
water passes, through the branchial clefts in the walls
of the pharynx, into the gill-pouches or into the gill-
chamber. There it is acted on by the gills, which
exchange their carbonic acid for its oxygen, and thence
it flows away through the external gill-clefts or through
the gill-slit.

In the circulation of the blood in Fishes venous blood
is carried to the heart whence it is propelled, by the
strong pulsations of the ventricle, to the gills, to be
arterialized. From the gills the arterial blood flows
into the dorsal aorta to be distributed to the body.

28 A Guide to the Zoological Collections

&'

Although the great majority of Elasmobranch Fishes have only five pairs
of gill-pouches, there are a few that have six or seven pairs. Again there is
one small section of the Elasmobranchs, namely, the Holocephali, in which
the external openings of the gill-pouches are concealed by a fold of skin that
encloses a rudimentary gill-cover.

Again, although the Teleosteans generally have four pairs of gills, there
are some, such as several of the Frog-fishes (Pediculati) that lead an inactive
life at the bottom of the sea, that have only two-and-a-half, or even only
two pairs.

Accessory Breathing Organs of Fishes. Gills are essen-
tially organs for aquatic respiration, but there are some
fishes that, living under peculiar conditions where the
supply of water may periodically run short, or where it
may suit them to take short journeys on land, are pro-
vided with accessory organs that enable them to breathe
out of water. Several such fishes are found in the
jheels of India. The so-called Climbing Perch (Anabas
scandens) and the Singhi fish [Saccobranchus fossilis), dis-
sections of both of which are exhibited in Case 10, are
good examples of these.

Observe in Anabas the frilled and pleated mass of
thin bone, covered by vascular mucous membrane, that
lies in a special prolongation of the gill-chamber, on
either side of the head. Observe in Saccobranchus the
lung-like extensions, into the muscles on either 'side of
the backbone, of the gill-chambers.

By these curious structures, if only they are kept
moist, the fish is able to breathe out of water, and it is
a well known fact that both these fishes will live for
days after they have been removed from water, if only
they are kept damp.

The Air-bladder or Swim-bladder of Fishes, a series
of dissections of which have been placed in Case 10,
can hardly be spoken of as an accessory breathing-

in the Fish Gallery of the Indian Museum. 29

organ ; but yet, since it is strictly homologous with the
lungs of air-breathing Vertebrates, and since in one
Sub-class of Fishes — the Dipnoi — it acts as a true lung,
a short account of it may be most naturally intro-
duced here.

The air-bladder (which does not exist in all Fishes
and is unknown among the Elasmobranchs) is a sack,
with tough walls and a pearly lustre, that lies in the
abdomen beneath the backbone and kidneys but above
the peritoneum or lining membrane of the abdominal
cavity. Its walls yield isinglass, and its cavity, in life,
is filled with gas, the amount and density of which can
be regulated in such a way as to make the organ an
adjustable float.

It originates as an outgrowth of the gullet, exactly in
the same way as do the lungs of higher vertebrates,
but in a large number of fishes its connexion with the
alimentary canal becomes completely obliterated.

The dissections in Case 10 show (1) an air-bladder of
a fresh-water eel that retains an open communication
with the gullet by means of a pneumatic duct; and (2)
various air-bladders that are mere closed hydrostatic
organs.

In the Dipnoi (Cases 23-24) the air-bladder is a true lung that receives a
special supply of venous blood and returns it— arterialized — to the heart. In
respect of their breathing-organs and circulation the Dipnoi resemble certain
Amphibia.

In many freshwater fishes the air-bladder (or special processes of it) is
connected with the internal ear.

The relations of the kidneys in Fishes are seen in
the dissections in Case 10. In the dissection of Trygon
(Elasmobranch type) they lie in the after portion of the

30 A Guide to the Zoological Collections

abdominal cavity on either side of the vertebral column
and their ducts open into the cloaca. In the dissections
of Pristipoma and Lates (Teleostean type) they adhere
to the backbone and open behind the vent.

The Nervous System of Fishes, portions of which
are illustrated by labelled dissections of an Indian
Carp, of a Bekti, of Lamprogrammus and of a Shark, in
Case ii, corresponds with that of higher vertebrates.

The Brain is small and is divided into five regions
none of which conceal any of the others in the Carp
and Lamprogrammus, though some of them do in the
Shark. The five regions are (i) the paired olfactory
lobes which are relatively large, (they have been re-
moved in Lamprogrammus to show the crossing of the
optic nerves) ; (2) the paired cerebral hemispheres, which
are small, though larger in the Shark than in the
others; (3) the paired optic lobes, which in the Carp and
Lamprogrammus are the largest lobes of the brain,
though in the Shark they are small and are completely
hidden by the cerebellum ; (4) the unpaired cerebellum
which is small in the Carp, but large in the Shark ; (5)
the medulla oblongata, which is continued without a
break into the spinal cord.

Immediately behind the cerebellum there is seen, in
a dorsal view, a hollow or groove, called the fourth
ventricle : this can be folloived forwards into the brain
and backwards into the spinal cord, betokening the
tubular origin of the central nervous system.

The olfactory lobes are prolonged to form the so-
called olfactory nerves, which expand where they meet
the olfactory sacks : observe the large size of these sacks

in the Fish Gallery of the Indian Museum. 31

in the Shark. The olfactory nerves are really out-
growths of the brain.

From the under surface of the optic lobes the optic
nerves pass : they too are really outgrowths of the brain.
In the Carp and Lamprogrammus the optic nerves cross,
so that the nerve of the right side goes bodily to the left
eye and vice versa : but in the Shark they fuse where
they cross each other.

Eight other pairs of nerves emerge from the under
surface of the brain. They supply the muscles that
move the eye-balls ; the skin and muscles of the head,
face, jaws, gill-covers and hyoid ; the organ of hearing ;
the mouth, tongue, gills and throat ; and the gullet,
stomach, heart, air-bladder and lateral line.

The Spinal cord is continued from the medulla oblon-
gata along more or less of the canal formed by the
neural arches of the vertebra?, and it gives off a pair of
spinal nerves between every vertebra.

The dissections of brains in Case 1 1 also display some
of the organs of special sense — namely the organs of
smell and hearing and the eye.

Except in the case of the Dipnoi, in which the nostrils
open into the mouth, the organ of smell in Fishes con-
sists of a pair of closed sacks of considerable size, the
lining membrane of which is pleated.

Except in certain fishes that inhabit subterranean
pools or ocean depths to which no light can penetrate
(e.g., Tauredophidium Hextii 'in Case 15), eyes are present
in Fishes and are peculiar in having the cornea fiat and
the lens'spherical.

The organ of hearing in Fishes is enclosed within the
bones of the head, and consists, on either side, of the
labyrinth or " internal ear " only. The cavity that
corresponds with the tympanum or " middle ear " of

32 A Guide to the Zoological Collections

higher vertebrates is either absent, or (as in Sharks) is
a functional part of the breathing apparatus ; and the
bones that correspond with the auditory ossicles of
higher vertebrates are in Fishes important parts of the
suspensorium of the jaws and hyoid.

The Muscular System of Fishes is comparatively
simple. The eye-balls, the jaws and gill-apparatus,
and the fins, all have their own special muscles, but the
principal part of the muscular system is massed along
the sides of the trunk and tail. Each lateral mass ol
muscles is longitudinally divided into a dorsal and
ventral band, and each of these again is split up,
vertically, into a close-fitting series of conical flakes or
segments known as myocommas.

The Electric ORGANS possessed by certain Fishes
are probably peculiar modifications of muscular tissue,
by means of which voluntary nervous impulses give
rise to powerful electric outbursts instead of to ordinary
tetanic contractions. A dissection of one of the elec-
tric organs of an Indian Torpedo, or Electric Ray,
showing the great nerves that ramify in its substance,
is exhibited in Case n. The electric organs are wea-
pons of defence and may also be useful in disabling
prey.

The phenomena of Reproduction in Fishes are
varied.

The form and position of the ripe organs of reproduc-
tion are shown in the dissection of Trygon and Pristi-
ftoma in Case 10, each representing a different type.

In the majority of Fishes the female lays eggs which
are fertilized by the male after their extrusion ; but in

in the Fish Gallery of the Indian Museum, 33

the Sharks and Rays, as well as in a few species of
Bony fishes, the eggs are impregnated by the male before
they are laid, as in the manner of Birds and Reptiles.
Moreover there is a considerable number of Sharks and
Rays in which not only are the ova fecundated inter-
nally but the embryos also complete their development
within the body of the parent, much as in the manner
of Mammals.

In the first case (external fertilization) the eggs are
small and shell-less and the embryo, of course, deve-
lopes, from first to last, quite independently of the
parent. The series of preparations in Case 12 illus-
trates the developmental history of the common Salmon
from the egg to the free-swimming larva.

In the Stickleback (of which a pair with nest and eggs are shown in
Case 12) the male builds a nest in which he induces certain females to lay
their eggs, and these eggs he guards jealously until they are hatched.

In the Sea-horse (of which a brooding male with the nursing-pouch laid
open is shown in Case 12) the male has an abdominal pouch into which the
eggs are received and in which they remain until development is complete
and larval growth well advanced.

And there are several other species of fishes in which one of the parents,
usually the male, watches over the developing offspring.

Where impregnation is internal, as among the Sharks
and Rays, the eggs are large, and they may either be
encased in a tough leathery shell, or they may be shell-
less : in the latter case they are not laid as eggs, but
undergo development within the oviduct, so that the
young are born alive.

In Case 12 the eggs and development of two species
of Dog-fish are exhibited : the eggs are enclosed in a
curious shell and are hatched quite independently of the
mother.

In the same Case (12) is shown a specimen of the
unborn young of a Hammerhead Shark. Here the
5

34 -^ Guide to the Zoological Collections

embryo developes in the mother's oviduct, and when all
the yolk is used up by the growing embryo, the large
empty yolk-sack adheres to the wall of the oviduct so
that the blood-vessels of the two structures — yolk-sack
and oviduct — come into close contact and allow nourish-
ment to pass from the mother to the embryo.

In the same Case (12) a specimen of the unborn
young of a Sting-ray (Trygon) is shown lying in the
mother's oviduct. Here too the embryo developes
within the oviduct, of which the lining membrane is
shaggy with glands that secrete a kind of milk. When
all the yolk is used up by the embryo, the yolk-sack,
which is small, shrivels, and then the embryo lives on
the milk which passes into its mouth through the
spiracles. In the exhibited specimen clusters of milk-
glands are seen to pass deep down into the spiracles.

There are certain Bony Fishes (see Saccogaster, Dip-
lacanthopoma , and Hephthocard) in which impregnation is
internal and the young do not leave the mother until
their development is complete. Here the eggs are
small, as in all Bony Fishes, and the growing embryos
appear to be nourished by simple absorption from the
wall of the ovary.

In some fishes the sexes differ considerably in appear-
ance, and it is generally the male that differs from the
female, either in being more brilliantly coloured or in
possessing special ornaments. Numerous instances of
these " secondary " sexual differences have been
brought together by Darwin, in the Descent of Man.
In Case 13 two good examples are shown; in one of
them {Brachypleura) the male has the first few rays of
the dorsal fin greatly lengthened to form an erectile
plume : in the other (Callionymus) the male alone has
both the dorsal and the caudal fin-rays much pro-
longed.

tn the Fish Gallery of the Indian Museum. 35

Observe also in Case 12 how the adult male alone of
the common Stickleback has the throat and belly
coloured bright red during the breeding-season.

Of the Habits and Uses of Fishes little can here be
said.

As to Uses : in every civilized country that has a sea-
board, the sea-fisheries are a recognized source of the
country's wealth and an acknowledged factor in its
commercial importance, besides often giving — as in the
case of Norway— a determining impulse to its scien-
tific, no less than to its industrial, activities. In India,
unfortunately, the sea-fisheries, although they are of
incalculable value, are almost entirely neglected by
capital, so that instead of contributing largely — as they
ought — to the national prosperity, they do little more
than furnish a contemptible living to the meagre popu-
lation of the coasts.

As regards Habits, these, as far as they have any
peculiar interest, will be referred to in the sequel.

A few words have yet to be said (1) as to the geogra-
phical relations of the Indian fish-fauna, and (2) on the
fishes that inhabit the great depths of the Indian Seas.

THE GEOGRAPHICAL RELATIONS OP THE FRESH-
WATER FISHES OF INDIA.

Exclusive of some marine forms that ascend tidal
rivers, the true fresh- water fishes of India number about
400 species, of which considerably more than half
(nearer two-thirds) are Carps {Cyprinidce)y and about
three-tenths are Cat-fishes (Siluridce.)

The Carps form an enormous dominant family and
are widely spread, in fresh waters, in Europe, Asia,
Africa, and North America : there is little difficulty in
explaining their presence and abundance in India.

36 A Guide to the Zoological Collections

The Silurida also form a very large family ; they are
not exclusively inhabitants of fresh-water, for some
species live in estuaries and in the sea, but always
near coasts. Though some species occur in North
America, in Europe, in Central Asia China and Japan,
and in Australia, the great bulk of the family are found
in Tropical America, Tropical Africa, and Southern and
Tropical Asia. Sometimes {e.g., Arms) the same genus
is represented in Tropical America, in Tropical Africa,
and in India.

The other true fresh-water fishes that are found in
India are

(3) the Cyprinodontidce, little carp-like fishes that also
occur in Tropical America, in Tropical Africa, and in
some of the countries bordering on the Mediterranean :

(4) the Chromides, a family of which most of the
members inhabit Tropical America, a considerable
number are found in Africa and Syria, and 2 species
only occur in India and Ceylon :

(5) the Symibranchidce, a small family of fresh- water
eels occurring only in Tropical America, in the Indian
region, and in Australia :

(6-9) the Notopteridac, the Labyrinthici, the Ophio-
cephalidce and the Rhyncholdellidce — all small families
that occur only in Africa and the Oriental region :

(10) the Na?idina, a small subfamily of Perch-like
fishes peculiar to India.

The fresh-water fishes of India thus show a curious
connexion with those of Tropical Africa and Tropical
America — a connexion that, if we can find other con-
firmatory evidence, would incline us to suppose that
the ancestors of the fresh-water fishes of India were
inhabitants of a great tropical sea that formerly
extended from Central America eastwards across
Africa far into Southern Asia.

in the Fish Gallery of the Indian Museum. 37

Besides the fresh-water families, there are a few spe-
cies belonging to the under-mentioned marine families
that have become adapted to fresh-water in this country,
namely : some species of Eels, Herrings, Garpikes,
Perches, Gobies, Grey-mullets, Parrot-fishes. These
fresh-water immigrants from marine families show us
one of the ways in which, in Delta-lands especially,
the fresh-water-fauna is being re-inforced from the sea.

THE GEOGRAPHICAL RELATIONS OF THE MARINE

FISHES OF INDIA.

Excluding the estuarine and brackish forms that are
passing into the fresh-water-fauna, the marine fishes of
India number about 1200 species. Most of them are
shore-fishes, a few inhabit the surface-waters of the open
sea, and a considerable number live in the great depths.

The total number of Indian genera is (allowing for
different opinions as to the limits of a genus) between
330 and 350, of which 54 per cent, are also found in
the Atlantic, and chiefly (though not entirely) in tropical
or subtropical latitudes of that ocean that embrace the
American shores and islands between 400 N. and io° S.
and the African shores and islands between the some-
what similar parallels.

Of the 54 per cent, that are common to the Atlantic
and the Indian Oceans, half — that is to say, 27 per cent.
of the total Indian genera — are also present in the
intervening Mediterranean Sea, and a certain number
(seventeen genera) that are absent from the Mediterra-
nean are present in the intervening Red Sea. Ten more
Indian Ocean genera that do not occur in the Atlantic
are found in the Mediterranean, so that the number of
genera that the Indian Seas have in common with the
Atlantic and Mediterranean combined is more than 54
per cent, of the total.

38 A Guide to the Zoological Collections

Not only so: but a respectable number of species are
common to the two areas, and that not only in the case
of wandering species that may live in the surface drift,
or of widely-ranging deep-sea species, but also in the
case of shore-keeping forms. For instance, Lobotes
surinamensis, a Sea-perch that lives in brackish water
and estuaries, is found on the Atlantic coasts of Tropical
America and on the shores of the Indian Ocean from
Africa to China, and has once been taken in the Medi-
terranean, off the Sicilian coast. Hoplostethus mediter-
raneum has a somewhat similar distribution, and there
are at least a dozen other species which, though not
found in the Mediterranean, are common to the Atlantic
approaches of that Sea and the Indo-Pacific.

The conclusion therefore seems irresistible that a
large part of the present fish-fauna of the Indian Seas
is derived from a great tropical Mediterranean Sea, of
a former geological period, that stretched from the Gulf
of Mexico, eastwards, halfway round the globe.

THE FAUNA OF THE DEEP SEA.

More than 150 species of fishes are known to live in
the depths of the Indian seas, down to 1500 fathoms.
Some of them undoubtedly live at the bottom, but the
great majority probably swim about in the middle
depths.

The conditions under which many of them must live
are most peculiar. In the first place, the direct heat
and light of the sun are cut off — as in a much minor
degree they are cut off to our own daily observation by
clouds and fogs — by the overlying volume of water, so
that the bottom of the sea, at great depths, is cold and
quite dark : at a depth of 200 fathoms it is supposed to be
quite dark, and the temperature in these seas, is about

in the Fish Gallery of the Indian Museum. 39

500 Fahr. : at 2000 fathoms there can be no doubt about
the absolute darkness, and the temperature, in these
seas, is constant at less than 2° above freezing-point.

As a result of the absence of sunlight, plants (except
perhaps microbes) do not exist.

Again the barometric pressure at the bottom of the
sea is something enormous : at 200 fathoms it must be
over 500 lb. on the square inch, at 2000 fathoms it must
be considerably over 2 tons on the square inch.

The effects of the pressure can only be inferred.
Deep-sea fishes when brought to the surface by the
dredge and released from the accustomed pressure,
are — only in a very highly intensified degree — somewhat
in the condition of a man who has been carried into the
uppermost regions of the atmosphere by a balloon.
They are dead : their bodies are distended and ruptured
by the expansion of their gases and by the extravasa-
tion of their fluids, and their eyes are blown out of their

sockets.

The ultimate effects of the darkness are as curious as
varied. Some deep-sea fishes are quite blind, their eyes
beino- hidden rudiments : Tauredophidium hextii shows
this. In others, the eyes are rudimentary and some of
the fin-rays have become long organs of touch — a com-
pensation on the principle of the blind-man's stick :
Bathypterois Giuitheri is a good instance. Others have
evolved their own means of illumination, and possess
organs that— like the luminous glands of fire-flies—
secrete a fatty substance that burns slowly with a cold
phosphorescent light : these have their eyes well deve-
loped, and several examples of them are shown in
Cases 15-18 in which a series of typical deep-sea fishes
are exhibited.

Ravenous as most fishes are, deep-sea fishes surpass

40 A Guide to the Zoological Collections

all others in this respect. Some of the models and
specimens in Cases 15-18 show the marvellous develop-
ments of teeth and maw.

The model of the deep-sea Torpedo, Bcnthobatis
moresbyi needs a special explanation, since it appears to
upset our calculations. It has been implied that Taure-
dophidium has lost its functional eyes because it lives in
the dark, and that certain other fishes although they
live in darkness, or, at any rate, in deep gloom, have
retained their eyes because they have acquired their
own means of illumination. But here is a fish Bentho-
batis moresbyi, which undoubtedly lives at the bottom
and at a depth to which sunlight does not penetrate,
and which — as we should therefore expect — is blind, but
which yet has, in the skin of its back, numerous little
luminous pores.

The probable explanation of this apparent anomaly
is that the pores are lures to attract prey — the prey
being then instantly killed or disabled by the powerful
electric organs which Bcnthobatis possesses.

in the Fish Gallery of the Indian Museum. 4 1

The following is the classification of fishes proper
adopted in this Gallery : —

Subclass I. Chondropterygii : —

Order i. PLAGIOSTOMA: —

Suborder 1. Sclachoidei (Sharks).
„ 2. Batoidei (Rays).

Order ii. Holocephala (Chi?nccras).

Subclass II. Dipnoi (Lepidosirens), not represented

in India.

Subclass III. Teleostomi : —

Order i. Ganoidei (Sturgeons), not represented
in India.

Order ii. Teleostei (Bony fishes) : —

Suborder 1. Physostomi.

„ 2. Acanthopterygii.

„ 3. Anacanthini.

„ 4. Lophobranchii.

„ 5. Plectognathi.

We shall begin with the Bony-fishes, as they are,
from the systematist's point of view, the latest, highest,
and most specialized developments of the fish type. It
must be remembered, however, that from the morpholo-
gist's point of view, this very specialization has brought
the Bony-fishes to a lower or rather more aberrant
grade of organization, compared with the central ideal
Vertebrate standard, than the Chondropterygii and
Dipnoi.

For the same reason we shall begin with the Acan-
thopterygii among the Bony- fishes.
6

42 A Guide to the Zoological Collections

Subclass TELEOSTOMI.

Order I. TELEOSTEI [Cases 42-75].

In the Bony-fishes the skeleton is completely ossified
and the tail is homocercal : the gills are free, and lie,
on each side, in a gill-chamber, which is closed by a
gill-cover and opens to the exterior by a single gill-slit :
the bulbus arteriosus is non-contractile : the intestine
has no spiral valve : the optic nerves cross each other.
The skin is usually, but not always, scaly : the scales are
usually either cycloid or ctenoid, but bony scutes resem-
bling ganoid scales occur in some species, and granules
something like placoid scales are occasionally met with.

Suborder AcANTHOPTERYGii [Cases 43-59] .

The Bekti is a good type of this suborder. Some of
the dorsal, anal, and ventral fin-rays are spines. The
air-bladder, when it is present, rarely has a pneumatic
duct.

There is really no hard and fast boundary line
between the Accuithoptcrygii and the Anacanthini and
Physostomi.

The Indian species of Acanthopterygian Fishes are
grouped in 42 Families.

Family I. Percidce [Cases 56-59].

The Perches are a large family to which about one-
tenth of all the Indian fishes at present known belong.
The Indian Perches are for the most part marine, a few
only — and those but small species — live exclusively in
fresh-water. The Bekti (Lates calcarifer) is the best
known of the many edible fishes of this family.

There are 31 genera of Indian Perches, of which
three — namely C/ielidoperca, Synagrops and Brcphostoma

in the Fish Gallery of the Indian Museum. 43

— have been discovered since the publication of the
Fauna of British India.

Brephostoma (Case 57) is a true deep-sea fish. Lobotes
surinamensis (Case 56) has a most curious and suggestive
range, being found along the Atlantic coast of Tropical
and Temperate America, in the Mediterranean, and
in the seas of India and China.

So far as is known, the Percidce first made their
appearance in Tertiary times. They are carnivorous.

Family II. Squamijnnnes [Case 55].

The Squamipinnes are practically Perches with a
compressed and greatly elevated body. They owe their
name to the fact that the dorsal and anal fins are so
thickly covered with scales that the usual boundary
beween the body and the fins is lost.

Most of them haunt coral-reefs and are gorgeously
coloured. Like the Perches they are carnivorous. They
are not much used as food, though Drepane punctata is
fairly good to eat.

The Indian species are arranged in nine genera. Scato-
phagus argus enters estuaries and backwaters, and is
even found in freshwater tanks that have long ceased to
be connected with any channel leading to the sea : it
thus illustrates the way in which the freshwater fauna
is continually being augmented from the sea.

Toxotes, which resembles Scatophagus in habitat, is
said to be able to shoot insects from plants overhanging
the water, by means of a jet forcibly ejected from its
mouth. An even more important interest attaches to
Toxotes, because although the species are now confined
to Oriental Seas, a fossil species has, according to Zittel,
been found in the Tertiary deposits of Monte Bolca near
Verona in Northern Italy.

44 A Guide to the Zoological Collections

Family III. Mtillidce [Case 55].

The Red Mullets are marine carnivorous fishes, the
great majority of which are confined to tropical seas.
Fourteen species, belonging to three genera that are
separated by very slight differences of dentition, occur
in Indian limits. They are all very good to eat.

Family IV. Spari&ce [Case 54] .

The Sea-breams are Perciform fishes that possess
curious specialized teeth for stripping and crushing the
shell-fish [Molluscd] upon which they largely feed. They
inhabit tropical and temperate seas, and twenty species,
belonging to seven different genera, are found in Indian
waters. They are all esteemed as food.

Sargus noct and Crenidens forskalii, two of the Indian
species, also occur in the Mediterranean. The genera
Sargus, Pagrus, and Chrysophrys are all found off the
Atlantic coasts of North America, in the Mediterranean,
and off the coasts of India.

Family V. Cirrhitidce [Case 53].

These are Perch-like fishes which are distinguished by
having the lower pectoral rays thickened and unbranch-
ed, so as to form either auxiliary organs of locomotion
or organs of touch. Four species, belonging to two
genera, are found in the seas of India.

Family VI. Scorpamidce [Case 53].

The Scorpcenidce are a largish family of marine, carni-
vorous, Perciform fishes, and are characterized by having
a bony stay or buttress across the cheek, and the bones
of the head and gill-covers usually armed with spines.

Many of them live among coral-reefs and have the
fin-rays curiously lengthened and fringed, and the skin

in the Fish Gallery of the Indian Museum. 45

studded with tags and tassels, to resemble the fronds of
sea-weeds and zoophytes. By this means they avoid
scaring — if they do not actually allure — prey, and also
escape the notice of their enemies. Minous inermis
(Case 14) has no such tassels, but has the body encrust-
ed with small Hydroid Zoophytes which make an even
better disguise.

Synanceia verrucosa (Cases 14 and 53), which in form
and coloration resembles a lump of encrusted rock, is
another instance of disguise for protective and offensive
purposes. This fish is also remarkable in having a series
of poison-glands connected with the spines of the dorsal
fin.

The majority of the Scorpamidai are of small size.

Family VII. Nandidce [Case 54].

In accordance with the arrangement followed in the
Fauna of British India, this family is allowed to stand
here. It is represented by Plesiops, which is really a
sea-perch ; and by three genera of small freshwater
fishes very distinct from Plesiops.

Plesiops haunts the pools of coral-reefs in the Indo-
Pacific region.

Badis, Nandus, and Pristolcpis are found in freshwater
in the East Indian region.

Family VIII. TeutJiididm [Case 53].

This small family contains the single genus Teuthis,
easily recognized (1) by the structure of the ventral fins,
each of which consists of two spines with three soft
rays between them, and (2) by the incisor teeth, which
are adapted for cutting sea-weed and coral. Tcuthis is
confined to the Indo-Pacific region, where it is found
among coral-reefs.

46 A Guide to the Zoological Collections

Family IX. Bcrycidce [Case 52].

This is one of the most ancient of all the families of
Bony-fishes (Teleostei) and was abundantly represented
in the seas of the Cretaceous period. It therefore, as
might be expected, is less sharply marked off than are its
fellows from some of the other suborders of Teleostei :
for instance, one genus, Melamphaes, was at first placed
near the Physostomous family Scopelidce ; and another
genus, Bathyclupea, was at first ranked among the
Herrings. Several members of the family, in fact, have
the air-bladder connected with the gullet by a pneumatic
duct, as in the typical Physostomi.

The antiquity of the family is also, in all probability,
the explanation of the fact that — the family being
entirely marine — most of its existing members are con-
fined to deep water.

The family being of exceptional interest, the Indian
genera may be noted in detail.

Genus 1. Monocentris. In this genus, which contains
but one species, M. /aponicus, the scales form a bony
mail, or carapace, and the ventral fins consist each of a
huge spine with a few rudimentary rays. M. japonicus
occurs in Japan, in Australian waters, in the Andaman
Sea, and off Mauritius.

Genus 2. HoplostctJius. This genus is only found at
depths of about 150 to 400 fathoms. H. Meditcrraneum
has a remarkable range, being found off the West Indies
and neighbouring coasts of America, in the Atlantic, in
the Mediterranean Sea, in the Arabian Sea and Bay of
Bengal, and in the Japanese Seas.

Genus 3. Trachiclithys. T. Darwinii has been found,
in deep water, off Madeira, in the Bay of Bengal, and
off Japan.

Genus 4. Batkyclupea. B. Hoskynii is peculiar to the

in the Fish Gallery of the Indian Museum. 47

Andaman Sea and Bay of Bengal, at considerable
depths. In form it much resembles a Herring, a resem-
blance that is further increased by the presence of a
perfect pneumatic duct.

Genus 5. Melamphaes. This is a curious form, which
is found only in very deep water. One species occurs
in the Bay of Bengal at a depth of over 1,300 fathoms.

Genus 6. Polymixia. The single species of this genus
bears a considerable resemblance to the Red Mullets,
since it has a pair of strong fleshy barbels. P. nobilis
has almost the same wide range as Hoplostethus medi-
terraneumy but has not been found in the Mediterranean
Sea.

Genera 7 and 8, Myripristis and Holocentrum, are both
shallow-water fishes, and are common enough to be used
as food.

Family X. Kuvtldce [Case 53].

This is a very small family of small marine Acantho-
pterygian fishes which have a thin body, one short dorsal
fin and a long anal fin.

Two genera, Kurtus and Pempheris, are known, and
they are only found in the Indian Ocean and Tropical
parts of the Pacific.

Family XL Polyncmidce [Case 53].

A small family of marine and estuarine fishes of much
economic value.

Polyncmus paradiseus, the Topsi or Mango fish, may
be taken as the type. In this fish there are two short
dorsal fins, remote from one another, and some of the
lower rays of the pectoral fins are isolated and prolonged
into independent tactile filaments of great length. The
" Topsi," although a marine fish, is seldom found far

48 A Guide to the Zoological Collections

from great estuaries, which at certain seasons it ascends,
even into freshwater limits. The eye is small and the
fish probably relies more on its tactile filaments than
upon its sense of sight. The use of the "Topsi" as
food is well known : equally estimable is the Silli fish,
which is also valuable for its isinglass.

Polynemus occurs in the West Indies, in the seas of
India, and in the tropical seas of the Western Pacific.

Family XII. Scicenidce [Cases 51-52].

In this family, the members of which share the
habitat of the " Topsi," there is a short spinous dorsal
fin and a very long soft dorsal fin.

It is a large family and is represented in Indian seas
by four genera — Sciccnay Scicenoides, Umbrina, and
Otolithus, all of which are very good to eat, besides being
capable of furnishing isinglass. All four genera range
from the Gulf of Mexico and neighbouring coasts of
America to the Atlantic and Mediterranean and east-
wards to the Indo-Pacific.

The Indian species are very common at the mouths of
the estuaries of big rivers, and several of them are able
to make a croaking sound : none of them appear to be
confined to freshwater, though several enter freshwater
freely.

Family XIII. XipliMdce [Case 51].

The " Sword-fishes " are characterized by having the
bones of the upper jaw prolonged to form a long
sword or lance of great sharpness and strength, and a
very formidable weapon of offence. By means of it
they are able to attack whales successfully ; and in the
Indian Museum there is a piece of ship's timber that has
been perforated by a sword-fish.

in the Fish Gallery of the Indian Museum. 49

In most of the species the dorsal fin is greatly elevated
and is said to be capable of acting as a sail.

They are the largest of all Acanthopterygians, and
they occur in the Atlantic, the Mediterranean, the
Indian Ocean, and the Pacific.

They must not be confused with the " Saw-fishes "
which belong to the same Order with the Sharks.

Family XIV. Trichluridce [Case 50].

A small family of highly rapacious marine fishes,
known as "Hairtails" and "Scabbard-fishes." The
body is low, compressed, and extremely elongate, and
the tail sometimes ends in a long filament. Scales are
absent or rudimentary. The dorsal and anal fins
consist of a very large number of rays.

Two genera— Trichiurus, with three species, and
Thyrsites, with one species-are represented in Indian
Seas Trichiurus occurs in the West Indies and Atlantic
and in Eastern Seas from India to Japan. Thyrsites
occurs in the West Indies and North and South Atlantic,
in the Mediterranean, and in the Indian and Western
Pacific regions: the Indian species comes from the
depths.

Family XV. Acronuridce [Case 50].

The « Surgeon-fishes " are a small family, the members
of which occur in shoals among coral-reefs. They are
recognized (1) by their rough leathery skin, (2) by the
presence of sharp-edged plates or spines on the sides of
the tail and (3) by their incisor teeth, which are adapted
for browsing on coral. The plates on the tail are
capable of inflicting severe injury, and I have seen a
man's palm slashed right across, down to the blood-
vessels, by the tail of one of these fishes.
7

50 A Guide to the Zoological Collections

The species found in Indian Seas are 16 in number
and belong to two genera, Acanthurus and Naseus.

Acanthurus is found in the West Indies and Tropical
Atlantic coasts of America, in the Red Sea, and in the
tropical parts of the Indian and Pacific Oceans. Naseus
is not found west of the Red Sea. Both genera, how-
ever, are known as fossils in the Tertiary deposits of
Monte Bolca in Northern Italy.

Family XVI. Carangidce [Cases 48, 49].

The " Horse-Mackerels " and their relatives are a
large family of active, predaceous, marine fishes, many
of which are used as food.

They are distinguished from the true Mackerels, which
they closely resemble in form and habit, by having
fewer vertebrae.

Many of them being inhabitants of the open seas,
have a very wide range in tropical latitudes. For
instance, Micropteryx chrysurus, Naucrates ductor, and
Trachynotus ovatus are all three found in the West Indies
and Atlantic and in the East Indies and Pacific,
Naucrates ductor also occurring in the Mediterranean and
in temperate seas. This fish is known as the Pilot-fish,
"from its habit of keeping company with ships and
large fish, especially Sharks."

The Indian genera Caranx, Trachynotus and Platax
occur fossil in the Tertiary deposits of Monte Bolca in
Northern Italy.

Family XVII. Cyttidce [Case 50].

The Dories are a small family of marine fishes which
is represented in Indian seas by a single species — Anti-
gonia capros. Besides occurring in these seas, this species
is found in the West Indies, off Madeira, in the East
Indian Archipelago, and off Japan — generally at a
considerable depth.

in the Fish Gallery of the Indian Museum. 5 1

Family XVIII. StroniateidcB [Case 48].

A very small family of marine fishes allied to the
Mackerels. The only Indian representatives are the
Pomfrets, justly celebrated for the table.

It is not generally known to the inhabitants of
Calcutta that Pomfrets abound off the Sandheads.

Other species of Pomfrets are found off the West
Indies and neighbouring coasts of America and in the
Mediterranean.

Family XIX. Covyplxcenidce [Case 48].

The so-called "Dolphins" are predaceous fishes of
the open sea, allied to the Mackerels. Two species
occur in Indian Seas. One of these, Coryphcena hipp-
uruSy ranges from the Atlantic to the Indian and
Pacific Oceans and is also found in the Mediterra-
nean.

Family XX. ScombridcB [Case 47].

The well-known family of Mackerels has seventeen
representatives in Indian waters, several of which,
known as " Seer-fish," run the Pomfrets very close in
estimation for the " equal feast/'

Like the " Dolphins" they are inhabitants of the open
sea and are among the most active and predaceous of all
fishes. To see and hear a shoal of Tunnies in pursuit of
a shoal of flying-fish — as may be done in the neighbour-
hood of the Laccadive Islands — is one of the sights
and sounds of the sea.

The following species range through the tropical parts
of the Atlantic and Pacific : — Thynnus thunnina, Thyn-
nus pelamys, Elacate nigra, Echeneis naucrates, Echeneis
remora, Echeneis brachyptera. All of these, with the
exception of Elacate nigra, are said to occur in the

A Guide to the Zoological Collections

Mediterranean also. The species of Echeneis also range
into temperate seas.

Echeneis^ known as the Remora, or " Sucker-fish,"
has the spinous dorsal fin most curiously modified to
form an oval cross-pleated disk, or sucker. By means
of this sucker, which is placed on the upper surface of
the head and neck, the fish can firmly attach itself to
other objects, such as fish, turtles, ships, and can thus
be carried about without exertion.

Family XXI. Trachinidce [Case 46].

This is a rather small family, the members of which
commonly have a long low body and a rather large
head, and mostly live on the bottom of the sea, in
shallow water or in moderate depths. They are rapaci-
ous, and they do not grow to any great size.

To the Indian genera recorded in the Fauna of British
India three more have to be added, namely, Champsodon,
Bembrops, and Chiasmodus, each represented by one
species.

Bembrops caudimacula (known to American naturalists
as Hypsicometes gobioides) has a most curious geographical
distribution : it is not uncommon in the Caribbean
Sea and off the neighbouring coasts of America at
depths varying from 68 to 324 fathoms, and in the
Andaman Sea and Bay of Bengal at 107 to 194 fathoms,
and it also occurs in Japan.

Chiasmodiis niger is one of the most voracious fishes
known, being able to swallow prey of greater bulk than
itself. It is an inhabitant of great depths, and has been
found off the West Indies, in the mid-Atlantic and off
Madeira, and in the Bav of Bengal.

The Trachinidcr in this Gallery include the Urano-
scopidce and Pseudochromides of Day's Fauna.

in the Fish Gallery of the Indian Museum. 53

Family XXII. Malacanthidce [Case 46].

This little family contains but one genus and three
species, one of which has been found off Ceylon.
Another species belongs to the West-Indian fauna.

Family XXIII. BatrachidcB [Case 46].

A small family represented in Indian Seas by two
species of Batrachus. They are of no great size and
have a broad thick head and a compressed tail, some-
thing like the Trachinida^ which family they also
resemble in habit. The ventral fins are peculiar in
consisting each of a spine and only two soft rays. The
other species of Batrachus extend from the Atlantic
coasts of America, through Indian and Pacific waters to
the Pacific coasts of Central America, one species occurr-
ing in the Mediterranean.

Family XXIV. Tediculati [Case 46].

The "Frog-Fishes" or " Fishing-Frogs " are charac-
terized (1) by their enormous head ; (2) by the curious
modification of the spines of the dorsal fin, which are
commonly transformed into tentacles ; (3) by the elonga-
tion, to form a sort of " arm,'"' of the bones on which the
pectoral fins are supported; (4) by the small size of the
gill-opening and the reduced number of gills. This
reduction of the breathing organs is, in all probability, a
consequence of the inactive life of the " Fishing-frogs,"
which either lie in wait for their prey on the bottom of
the sea, or — as in the case of several species of Anten-
narius — adhere to drift sea-weed.

The Indian genera of this remarkable family may be
reviewed in detail.

Genus 1. Antennarim. The species of this genus are
pelagic and are often remarkably coloured to harmonize

54 A Guide to the Zoological Collections

with the colours of the sea-weeds, encrusted rocks, etc.,
to which they cling with their arm-like pectoral fins.
They are the only Indian Pediculates that possess an
air-bladder.

Genus 2. Lophius. The Fishing-frogs proper live on
the bottom. They have a large disk-like head and
a cavernous mouth with numerous sharp teeth sloping in-
wards. The first dorsal spine is very long and ends in
a tassel ; and it can be bent forwards so that the tassel
hangs in front of the mouth. This long modified spine
and its tassel form, in fact, a fishing-rod and bait. The
fish lies concealed in the mud at the bottom of the sea,
the concealment being assisted not only by the colour
of the fish but also by the curious frond-like tags of skin
with which its body and fins are fringed : in this position
it "plays" its fishing-rod, and, when other fish are attract-
ed to the bait, has only to open its enormous mouth.
Four species of Lophius are found in Indian waters, at
depths between 25 and 400 fathoms. The other species of
Lophius occur in all parts of the Atlantic, in the Mediter-
ranean, and in the seas opening into the Western Pacific.
Genus 3. Ceratias. One species of this genus is found
in Indian waters. It lives at great depths, and its
habits are probably the same as those of Lophius ; but,
as there is no daylight at these depths, the lure at the
end of the " fishing-rod " is a luminous organ, which,
in all probability, is extremely efficacious, as fishes are
known to be readily attracted by a light. The other
species of Ceratias occur at great depths off the coast
of Greenland, in the Atlantic, and in the seas of the
Western Pacific system.

Genus 4. Onirodes. One species is an inhabitant of
the great depths of the Bay of Bengal. It chiefly differs
from Ceratias in having a smooth skin. The only other
species known was taken off the coast of Greenland.

in the Fish Gallery of the Indian Museum. 55

Genus 5. Chaunax. In this genus the modified first
dorsal spine, or tentacle, is short. One species is known
and has been found at depths of 130 to about 400
fathoms, off the West Indies and neighbouring American
coasts ; off Madeira, Cape Verde and the neighbouring
African coasts ; in the Arabian Sea and Bay of Bengal ;
in Japanese Seas ; and off the Fiji Islands. Like
many other deep-sea animals, Chaunax p ictus is of a
beautiful red or pink colour.

Genus 6. Halieutcea. In this genus the form of the
body is much like that of Lophius, but the modified
dorsal spine, or tentacle, is situated on the snout, where
it can be retracted into a bony cavity. Four species are
found in Indian waters, three of them at considerable
depths.

Genus 7. Dibranchus. This genus is distinguished
from Halieutcca by having only two pairs of gills instead
of two and a half pairs. Two species occur in Indian
seas, both at depths of about 200 to about 400 fathoms.
Another species is found in the Atlantic.

Genus 8. Malthopsis. This genus differs from Di-
branchus in little but dentition. In habit it resembles
Lophius and other forms. The type species occurs in
Indian seas at depths similar to those at which Di-
branchus is found. A second species has lately been
found off the Sandwich Islands.

Genus 9. Halicmetus. This form differs from Malthopsis
only in having no soft dorsal fin. Only one species is
known, which shares the bathybial habitat of Malthopsis
and Dibranchus.

Family XXV. Cottidce [Case 46].

A small family of Fishes, resembling the Trachinidce
in form and habit. Some of the bones of the head are

56 A Guide to the Zoological Collections

armed with spines, and there is a bony buttress across
the cheek, as in the Scor pallida. In the Gurnards
{Trigla and Lepidotrigld) some of the rays of the pectoral
fins are thickened and isolated from the rest of the fin to
serve partly as organs of touch and partly as organs for
creeping along the bottom of the sea.

The Indian genera are Platycephalus, Trigla, and
Lepidotrigla.

Family XXVI. Cataptiracti [Case 45].

The Mailed Gurnards differ from the Gurnards in
having the head and body protected by bony plates.
When the head alone is thus protected the scales of the
body are keeled. The Indian genera are Peristethium,
Dactyloptcrus and Pegasus. In Dactylopterus the pectoral
fins are prolonged, as in the true Flying-fishes, to form
organs of flight.

Family XXVII. Gobiidce [Case 45].

This is a very large family, the Indian species alone
numbering 91. None of them grow to any size, most of
them are littoral, and some inhabit freshwater. Some
of the Gobies construct nests. The species of Perioph-
thalmus and Boleophthalmus live among tidal creeks,
and are as much at home on land as in water, hopping
about with great activity by means of their strong
ventral and pectoral fins. One of the most curious
sights of the estuary-land of this country is to see
Periophtlialmus sitting up on its arm-like pectoral fins
and gazing in all directions with its large protruding
swivel eyes. The Dragonets {Callionymus) are often
beautifully coloured, and in several species the male is
much more brilliant than the female, and has the rays
of the spinous dorsal and of the caudal fin greatly
prolonged.

in the Fish Gallery of the Indian Museum. 57

Family XXVIII. BlenniidcB [Case 45].

A large family of fishes much resembling the Gobies
in form, and, like them, inhabitants of the littoral and of
brackish and fresh water. Thirty-seven Indian species
are known, and none of them attain any great size. One
of the European species of Blennies brings forth its
young alive. Tripterygiam occurs in the Mediterranean
Sea, in East Indian waters, and in New Zealand. In
several respects the Blcnniidee illustrate the transition
from the Acanthopterygii to the Anacanthini.

Family XXIX. Trichonotidce [Case 45].

Two species of this small family, which is allied to
the Blenniidcc, occur in Indian Seas, namely, Trichonotus
setiger and Tamiolabrus cyclograptus.

Family XXX. Cepolidm [Case 45].

This family contains a single small genus, Ccpola, of
which two species are found in the seas of India. On
account of their elongate compressed body they are
known as Band-fishes. The other species occur in the
Eastern North Atlantic, the Mediterranean, the East
Indian Archipelago, and the seas of China and Japan.

Family XXXI. Mastacembelidce [Case 45].

The " Spiny-eels " live chiefly in fresh, but also in
brackish water, in West Africa, Syria, India, Ceylon,
and Further India. Several species are common in the
jheels of Bengal, where they are known as Gondii and
Bdmmi. They are eaten by the people of the country,
their flesh being said to be tough but good.

Family XXXII. Sphyvcenidce [Case 45].

This small family includes a single genus, Sphyrcenay
8

58 A Guide to the Zoological Collections

of which four species live in Indian Seas. They are
large, active, and extremely rapacious fishes. The other
species are found in the West Indies and Atlantic, in
the Mediterranean and Red Seas, and in the Indo-
Pacific.

Family XXXIII. AtJierinidce [Case 44].

A small family allied both to the Sphyramida and to
the Grey Mullets. They are marine, but also ascend
rivers. Four species of Atherina occur in India, the
other species of the genus being found in the North and
South Atlantic ; the Mediterranean, Black, and Red
Seas ; and the seas of the Indo-Pacific region

Family XXXIV. Mugilidce [Case 44].

The Grey Mullets are numerous in temperate and
tropical seas, occurring in shoals. They are particularly
fond of brackish water and tidal pools, and some of the
species are entirely fluviatile, living far above the reach
of the tides. They feed to a large extent by sifting the
organic matter out of mud and sand, and their digestive
canal is singular, not only for its great length, but
also in having the stomach provided with a muscular
chamber much like the gizzard of birds. In correlation
with their method of feeding, the gill-rakers, or struc-
tures for straining the water before it passes over the
gills, are remarkably developed. They are good eating
when perfectly fresh.

Family XXXV. Fistulariidce [Case 45].

The Tube-fishes have the anterior bones of the head
produced to form a long tube, at the end of which the
mouth is placed. One species is found, often in back-
waters of the sea, in India.

in the Fish Gallery of the Indian Museum. 59

Family XXXVI. Ccntriscidw [Case 45].

A very small family, represented in Indian seas by a
single species. The anterior bones of the head are
produced to form a long tube, with the mouth at the
end, as in the Fistulariidtz. In the Indian species the
back is enclosed in a cuirass formed not by scales, but
by modifications of the backbone. The existing species
of Amphisile are confined to the Indo-Pacific ; but a
fossil species has been found in the Tertiary deposits of
Monte Bolca in Northern Italy.

Family XXXVII. Opliioceplialidce [Case 44].

This is a small family of freshwater fishes, most of
which belong to the Oriental region, one or two species
only occurring in Africa. They are common in the
jheels and tanks of Bengal, where they are known as
Murral. The gill-chamber is connected with a cavity
in the head which acts like the pulmonary sack of a
snail, so that if the air is only kept moist the fish can
breathe out of water. Some of the species that live in
jheels and tanks undoubtedly, during the dry season,
exist, buried in the mud, in a state of suspended anima-
tion, from which they recover when the tank fills up
again in the rains. They are largely eaten in Bengal.

Family XXXVIII. Labyrinthici [Case 44].

In habit, the fishes of this family resemble the Ophioceph-
alidir, and like them can bear removal from water, and
can stand being dried up in the mud of jheels and tanks
during the hot weather. The gill-chamber also is con-
nected with a cavity in the skull ; but this, in place of
being a simple cavity, is filled by a coiled and pleated
plate of very thin bone, by which the respiratory surface
is much increased. The Koi, or " Climbing-perch,"

6o A Guide to the Zoological Collections

Anabas scandcns, is a good example of the family. The
climbing-perch is said to be able to climb trees : it
certainly can and does escape from a tub half-full of
water unless means are taken to prevent it. The " Koi "
and its congeners are popular as food, their flesh being
believed to be very strengthening.

Family XXXIX. Trachypteridce [Case 45].

The Ribbon-fishes have a long, low, thin, tape-like
body, at the end of which the caudal fin sticks up almost
at a right-angle. 'I he only Indian species known is
Rcgalccus Russcllii. The other species of Regalecus come
from the North and South Atlantic, the Mediterranean,
and the seas of New Zealand.

Family XL. GlyphidodontidcB [Case 41].

A largish family of fishes that, for the most part, live
among coral-reefs and are gorgeously coloured. They
have a considerable resemblance to some of the Sea-
perches and SquamipimieSy but are distinguished from
them by having only oh pairs of gills and the lower
pharyngeal bones fused. Of the six Indian genera three,
namely Pomaccntrus, Glyphidodon and Ueliastes, range
throughout the tropical parts of the Indo-Pacific and are
also found off the Atlantic coasts of Tropical America,
Heliastes also occurring in the Mediterranean. They are
carnivorous and feed largely on the polyps, etc., of the
reefs.

Family XLI. Labvidce [Case 43J.

The Wrasses are a large family, the members of which
are found in all tropical and temperate seas, not far from
the shore. They resemble the members of the previous
family in having 3J pairs of gills and the pharyngeal

in the Fish Gallery of the Indian Museum. 6 1

bones fused, but differ from them in the form of the
scales, which are cycloid, and in having very strong-
teeth for crushing the shells of the mollusks upon which
they largely feed. Many of the species have very thick
lips. Like the Glyphidodontidcc many of them are coloured
in patterns of startling brilliance. The Indian species
number nearly sixty. Of the 20 Indian genera, eight
(namely, Cossyphits, Platyglossus, Novacula, Juh's, Coris,
Scarusy Callyodon, Pseudoscarus) range through tropical
seas from the Atlantic coast of America through the
Pacific, Novacula, Juh's, Cons, and Scarus also occurring
in the Mediterranean.

Family XLII. Chvomides [Case 44].

The Chromides are a small family of fishes inhabiting
rivers and lakes in Tropical America, Tropical Africa,
Madagascar and Palestine, and three species are found
in India, two of which also occur in Ceylon. In the
structure of the pharyngeal bones they agree with the
Wrasses and Glyphidodonts. They are, for the most
part, small.

Suborder Anacanthini [Cases 42, 43].

None of the fins have spines. The ventral fins, if
present, are often jugular. The air-bladder, if present,
has no pneumatic duct.

This suborder is divided into two sections (1) the
Gadoidei, or Cod-fishes, and (2) the Plcuronectoidei, or
Flat-fishes.

Anacanthini Gadoidei [Cases 42, 43].
The Indian Gadoidei are, for the most part, but
not entirely, inhabitants of the depths, where the

62 A Guide to the Zoological Collections

temperature approaches that of temperate, or even of
Arctic, seas ; and they are grouped into four families.

Family I. Gadidce [Case 42].

Three species of the Cod family inhabit Indian Seas,
namely Bregmaceros Macclellandii, Physiculus roseus and
Pliysiculus argyropastus.

The first is common enough in Indian waters at fifty
to about a hundred and fifty fathoms, but also occurs
at less depths : the second has been found in the Anda-
man Sea at about 200 fathoms, where the temperature
is about 56° Fahr. : the third has been taken in the Bay
of Bengal and Gulf of Manar between 100 and 200
fathoms, where the temperature is between 60° and
50° Fahr.

Another species of Bregmaceros occurs in the Carib-
bean Sea ; and other species of Physiculus occur in the
West Indian and Madeiran regions of the Atlantic, in
the Mediterranean, and in Japanese Seas.

Family II. Opliidiidce [Case 42].

The great majority of the Indian representatives of
this family live in the cool depths of the sea. The body
is generally long and somewhat eel-like : the ventral
fins are reduced to one or two rudiments attached to the
throat, or are altogether absent. The genera may be
noticed in detail : —

Genus 1. Brotula. The species, which occur in the
Caribbean Sea, the Indian Ocean and Japan, have small
barbels on the chin.

Genus 2. Dincmatichthys. A species has been found
in the pools of the coral reefs of the Andamans. It has
a distinct caudal fin.

Genus 3. NeobytJiites. This is a deep-sea genus, of

in the Fish Gallery of the Indian Museum. 63

which six species are found in the seas of India between
100 and 1700 fathoms. The head and body of all are
covered with small scales.

Genus 4. Dicrolene. Also a deep-sea genus, differ-
ing from Neobythites only in having some of the lower
rays of the pectoral fin isolated and greatly prolonged
to form organs of touch something like those of the
Topsi fish. Three Indian species are known, of which
one, Dicrolene intronigra, also occurs off the West Indies
and neighbouring American coasts and off the Atlantic
coasts of north-west Africa.

Genus 5. Bassozetus. Another deep-sea genus, differ-
ing from Neobythites chiefly in being- more eel-like in
appearance. The only Indian species comes from the
Bay of Bengal in 1310 fathoms of water.

Genus 6. Dermatorus. Another deep-sea form, differ-
ing from Bassozetus chiefly in having the bones of the
head armed with spines. Three Indian species are
known from depths between 900 and 1800 fathoms.

Genus 7. Glyptophidium. Two species belong to the
Indian fauna, living at depths between 150 and 400
fathoms. In both, the bones of the head are curiously
crested and frilled.

Genus 8. Lamprogrammus. In this curious form there
are no ventral fins and the scales of the lateral line are
much enlarged, — each scale also carrying a gland that
probably secretes light. Two species are known and
they have only been found between 400 and 700 fathoms.

Genus 9. Tauredophidium. This is a true deep-sea
form of which only one species is known, occurring in
the Bay of Bengal at a depth of 1310 fathoms. It has
no eyes, and the bones of the gill-covers are armed with
enormous spines which can be erected in defence.

Genus 10. Diplacanthopoma. Also a member of the

64 A Guide to the Zoological Collections

deep-sea fauna. The head is covered with a thick
glandular scaleless skin. Of the three Indian species
one is known to be, and all are believed to be, vivipar-
ous, and one also occurs in the Atlantic off the coast of
Brazil.

Genus 11. Saccogaster. Another deep-sea genus,
viviparous like Diplacanthopoma, from which it chiefly
differs in dentition.

Genus 12. Hephthocara. Another deep-sea and vivi-
parous form, resembling the two previous genera in
having the head covered by a peculiarly thick glandular
scaleless skin, but differing from them in being desti-
tute of ventral fins.

Genus 13. Fierasfer. A curious eel-like shallow- water
genus of peculiar habits. In the Case containing the
Holotliuroidea, in the Invertebrate Gallery, is a dissec-
tion of a Holothurian with a fish of this genus in its
body-cavity. In life the Fierasfer is semi-parasitic on
the Holothurian, entering and leaving its host's body
through the cloaca, the wall of which it appears to
rupture. One species occurs in these seas, other species
being found in the Atlantic, the Mediterranean, and in
other parts of the Indo-Pacific.

Genus 14. Bleekcria. Allied to the " Sand-eels " of
Europe. One species has been found on the Madras
Coast.

Family III. Macrwridce [Case 42].

Like the majority of the Ophidiida, the Macruridce,
whether of India or elsewhere, are all inhabitants of the
cold waters of the deep sea. Their body ends in a long
lash-like tail, and in most of the species the scales are
keeled, or spiny, or both. The ventral fins are well
developed. Two genera are represented in Indian seas,

in the Fish Gallery of the Indian Museum. 65

namely Macrurus with 16 species, and Bathygadus with
2 species. Macrurus cavemosus, which is not uncommon
in the Andaman Sea and Gulf of Manar at ISO to 405
fathoms, also occurs in the Gulf of Mexico, and is very
probably identical with the Mediterranean Macrurus
italicus. Macrurus la-vis, of which several specimens
have been taken in the Andaman Sea at 188 to 419
fathoms, and in the Arabian Sea at 719 fathoms, also
occurs in all parts of the North Atlantic system, off the
coast of Brazil, off Madeira and its neighbourhood, in
the Mediterranean, and off the Sandwich Is. Bathygadus
longifilis is another Indian species that is found off
the Atlantic coasts of America, and in the Madeiran
neighbourhood.

Family IV. Atcleojyodidce [Case 42].

Two closely similar species, one from the depths of
the Indian seas, the other from Japan, make up this
family. The body is shaped like that of Afacrurus,
but there are no scales and the ventral fins are reduced
each to a single stiff filament. In the Indian species,
Ateleopus indicus, the mouth looks as if it were adapted
for suction : this species has been found in the Anda-
man Sea, at 188 to 405 fathoms, and off the Malabar
coast, at 224 to 284 fathoms.

Anacanthini Pleuronectoidei.

This section includes the single large family of Pleuro-
nectidas or Flat-fishes.

Family V. Pleuronectidce [Cases 42, 43].

In the Flat-fishes the head and part of the body
have departed from the bilateral symmetry that charac-
terizes all the Craniate Vertebrates.
9

66 A Guide to the Zoological Collections

The Flat-fishes have the body compressed like a leaf,
and lie habitually on one side — either the right or the
left — both eyes being placed on one side of the body,
namely on the side opposite to that on which the indivi-
dual lies. Except in a few deep-sea species the side
upon which they rest is colourless ; and in all but a few
pelagic forms the side upon which the eyes are situated
is coloured, the colouration being, for protective pur-
poses, very similar to that of the sand or mud or shingle
on which the fish rests.

In the very youngest stages of their existence Flat-
fishes are bilaterally symmetrical, and swim in a verti-
cal position, like other fishes ; but as soon as they
begin to rest upon one side, which happens very early
in life while the tissues are plastic, the eye and orbit
of that side become twisted round towards the light,
until both eyes come to be on the upper side of the
body.

Flat-fishes occur in all seas : they always live on the
bottom, preferably on a sandy bottom. A good many
species live in estuaries, and a few live exclusively in
fresh water. Sixty-four different species are found in
Indian waters, but none of them reach any great size.

The Flat-fishes of Indian seas are very good to eat,
but they are very seldom brought to market.

The Indian species belong to the following generic
groups : —

(1) Shallow-water genera: — Psettodes, Amoglossus,
PseudorhonibuSy Rhomboidiclithys, Psettyllis, Citharicht/iys,
Scwiaris, Brachypleuray Solea (including Achirus\
Synaptura, Plagusia, Cynoglossits.

(2) Deep-water genera : — Chascanopsetta, Lccops, Boo-
psetta, Aphorislia.

Aphoristia, of which four species have been found at

in the Fish Gallery of the Indian Museum. 67

moderate depths in Indian seas, is interesting because
it is only known to occur elsewhere off the Atlantic
coast of America.

Suborder PHYSOSTOMI [Cases 60-73].

The Ruhu, the Tengra and the Hilsa are good familiar
types of this suborder. The rays of the fins, with the
exception sometimes of the first dorsal and first pectoral
rays, are not ossified. The ventral fins, when they are
present, are placed behind the pectoral fins — usually a
good long way behind them. The air-bladder, when
present, is usually connected with the gullet, or with
some part of the intestinal canal, by a pneumatic duct.
(See the air-bladder and pneumatic duct of an eel in
Case 10).

The fishes of this suborder are grouped into the
following 14 families.

Family I. Slluvklce [Cases 60-63].

The Cat-fishes are a very large family, the Indian
species alone numbering nearly 120. For the most part
they inhabit fresh waters, but a few live in the sea —
generally in the neighbourhood of estuaries, and never
far from the coast. Many of them are used as food,
except by Mahomedans. The Cat-fishes are so-called
from the barbels, which are attached to the lips
and jaws, and somewhat resemble in appearance the
" whiskers ' of a cat. These barbels are organs of
touch, for Cat-fishes usually live in muddy water where
the sense of sight is not of much use : for this reason
also, their eyes are usually small. The skin is scaleless.
In most of the species the first spine of the dorsal fin

68 A Guide to the Zoological Collections

and the outermost spine of each pectoral fin is enor-
mously enlarged and thickened and dreadfully barbed,
so as to form a formidable defensive weapon. In some
species [e.g. Plotosus) the wound inflicted by these
spines is as painful as the sting of a scorpion, and causes
a hurt that may be dangerous. The neighbouring
bones are specially strengthened for the support of these
great erectile spines. In Arius and Osteogeniosus the
males carry the fertilized ova in their mouths, probably
in order that the developing embryos may benefit by the
streams of fresh water as they pass into the gill-chamber
of the parent. In Exostoma, which lives in rapid
mountain streams, the lips form a sucker and the front
part of the belly forms a sort of adhesive pad, by
means of which the fish can attach itself to fixed
objects. Ckaca, which is not uncommon in the jheels
of Bengal, has the mode of life and much the external
appearance of a Frog-fish. In Saccobranchus (the Singhi)
each gill-chamber is prolonged to form a respiratory sack
that lies alongside the backbone, and enables this fish
to breathe out of water. In Glyptosternum which lives
in quick-flowing rivers, the pectoral fins are horizon-
tally expanded, and the surface between their bases is
pleated, to form an adhesive mooring apparatus. The
curiously wide distribution of the Siluroids has already
been commented upon.

Family II. Scopelidce [Cases 70-71].

The members of this family are entirely marine, most
of them being either pelagic or living in the depths of
the ocean. One Indian species, the " Bummalo " or
" Bombay Duck," has a certain repute as food. The
genera may be noticed in detail.

Genus 1. Scopelarchus, known only from the depths of

in the Fish Gallery of the Indian Museum. 69

the Arabian Sea : it is a generalized form, linking
together several other genera that have usually been
regarded as widely separated. It has a scaly body, a
formidable dentition, and eyes with a strong upward
cast, but it has no phosphorescent organs.

Genus 2. Saurus : a shore genus, ranging, in tropical
and subtropical latitudes, from the West Indies, across
the Atlantic, to the Mediterranean, and across the Indian
and Pacific Oceans. It has a scaly body, lateral eyes,
no barbed teeth, and no phosphorescent organs.

Genus 3. Saurida : only differs from Saurus in some
particulars of dentition : it does not occur in the Mediter-
ranean.

Genus 4>. Harpodon : is singular in having a three-
lobed tail : it has formidable barbed teeth. The
" Bombay duck" belongs to this genus, which includes
only three species. The body may be completely or
only partly scaly.

Genus 5. Chlorophthalmus : a deep-sea genus, with a
distribution similar to that of Saurus. It has enormous
eyes and tiny incipient phosphorescent organs, and its
scales are well developed.

Genus 6. Bathypterois : a scaly deep-sea genus of the
Atlantic, Indian, and Western and Southern Pacific
Oceans. It has very small, almost rudimentary, eyes
but in compensation for this, some of the fin-rays are
wonderfully prolonged and strengthened to form organs
of touch.

Genus 7. Scope lus : a large and very widely ranging
oceanic genus, with a scaly body and with definitely-
arranged phosphorescent spots. Most of the species
are quite small.

Genus 8. Neoscopelus, differs from Scopelus only in
having a flat snout and a smaller mouth, and in the

70 A Guide to the Zoological Collections

different position of the anal fin. One species is known,
which occurs in the Atlantic, in the seas of India, and
in the south-western Pacific.

Genus 9. Scopelengys : another deep-sea genus, of
which only one species is known.

Genus 10. Odontostomus. This genus, which includes
two species — one from the Mediterranean, the other
from the Bay of Bengal and Andaman Sea — is alone
among Indian Scopclidoe in having the body scaleless :
its eyes have a very strong upward cast and its teeth
are most terrible.

Family III. Cypvinidce [Cases 64-67 J.

The Carps and Loaches are an exclusively fresh-water
family of enormous size, and are widely distributed
throughout the Old World and North America. The
Indian species alone number over 230. The family
being exposed to such wonderfully diversified conditions
of life, its members exhibit a corresponding diversity of
form. The widest departure from the typical carp form
is seen among those species, such as Oreinus, Schizo-
thorax, Ptychobarbus, and Diptychits, that live in the
spating rivers of Tibet, Kashmir, and of the Oxus system.
These forms, dwelling under conditions very similar to
those that have, in other regions, produced the Trout,
have come to, superficially, resemble Trout so closely
that European travellers habitually call them " trout,"
though they are undoubted carps: this is particularly
the case with Ptychobarbus, which is even spotted like
a trout.

The famous " Mahseer" is a carp of the Barbel kind.

Most of the fishes eaten by Europeans up-country are
carps.

The different kinds of " Gold-fish " are domesticated

in the Fish Gallery of the Indian Aluseum. 7 1

varieties of a species of carp. In a state of nature all
such varieties and monstrosities are — the conditions of
life remaining unchanged — kept down by an inexorable
competition ; but when Man interposes, he can, within
reasonable limits, preserve any variety or monstrosity
that takes his fancy. Of course there are some animals
that are not only more variable and plastic but also
more amenable to domestication than others, and the
Gold-fish appears to be one of these.

Family IV. C ypvinodontidce [Case 67].

The interest of this family of fresh-water fishes — of
which 5 species are found in India — has been noticed in
the section on Geographical Distribution.

Family V. Scombresocidce [Cases 70-71].

This family includes the Gar-pikes and Flying-fishes.
The Gar-pikes are marine, but have a tendency to pass
into estuaries and backwaters and so to furnish a com-
plement to the freshwater fauna. The Flying-fishes
are truly oceanic and are found in all the oceans in the
tropical and temperate zones. The Indian Gar-pikes,
Belune and Hemiramphus, also occur in all tropical and
temperate seas, including the Mediterranean.

Family VI. Sternoptychidce [Case 70].

These are oceanic fishes which live at a considerable
depth below the surface. Their eyes are well developed
and their phosphorescent glands are abundant. The
genera that occur in Indian seas are Argyropclecus,
Sternoptyx, Polyipnus, Cyclothone, Photichthys, and Chan-
liodus. Of these, all but Polyipnus and Photichthys are
also found in the Atlantic; while Argyropelecus and
Chauliodus are also Mediterranean genera. In Polyipnus

72 A Guide to the Zoological Collections

the number of phosphorescent organs is enormous :
in Chauliodus the teeth are of the most cruel size and
form.

Family VII. Stomiatidce [Case 71].

These are also oceanic fishes, living in darkness at
considerable depths, but furnished with phosphorescent
organs, and having teeth of astonishing size and sharp-
ness. They are easily distinguished by having a barbel
attached to the hyoid bone, and this barbel may either
hang down free, or may be attached to the inside of the
chin. The Indian genera are three in number, namely,
Stomias, Malacosteus, and P/iotostomzas, all of which also
occur in the Atlantic, Stomias being also found in the
Mediterranean.

Photostomias and Malacosteus are perhaps, for their
size, the most rapacious-looking fish of these seas :
their mouth is so enormous that it forms one great cleft
with the gill-openings, and almost separates the head
from the body : the fangs are large and peculiarly sharp,
and the lower jaw looks more like a hideous spring rat-
trap than a jaw.

Family VIII. Clupeidce [Cases 68-69].

The Herrings are a large family and are of the great-
est use to Man. They live in shoals, generally near
shores and estuaries ; some, such as the Hilsa, enter
rivers, and a few live entirely in fresh water. The
Indian genera Clupea (Herring) and Eugraulis (Anchovy)
have a wide distribution in the Atlantic and Indo-Pacific,
and also occur in the Mediterranean. The Indian genera
Pellona, Opisthopterus, Raconda, Chaloessus, Spratel-
loidcs, Albula, Plops, Megalops all occur in the Atlantic :
so that out of 14 genera of Clupeido: that are represented

til the FisJi Gallery of ttie Indian Museum. 73

in India, only four are peculiar to the Indo-Pacific
region. In the case of Albula, the same species [Albula
conorhynchus) is found off the West Indies and neigh-
bouring coasts, off Cape Verde and its vicinity, in the
Red Sea, and off the coasts of the Oriental Region. In
the case of Elops, the same species {Elops saurus) is
found in the West Indian Region, at the Cape of Good
Hope and off the shores of East Africa, and in Oriental
seas. This distribution of genera of a family that
dates from Cretaceous times, corresponding as it does
with that of the Berycidce and Scopelida', both of which
are contemporary with the Herrings, is highly interest-
ing. Among the existing Indian Herrings the most
important is the Hilsa, the economic possibilities of
which are enormous ; for it is a true herrring {Clupea)
and lends itself to capture in shoals, and is undoubtedly
as fit to be salted and smoked as its congener of British
seas.

Family IX. Chirocentridce [Case 69].

This family contains a single genus and species,
CJiirocentrus dorab, peculiar to the Indian Ocean. It has
a resemblance to a Herring, but the body is low and ex-
tremely long.

Family X. Alepoceplialidce [Case 68].

The members of this family are found only in the
depths of the sea : they are closely related to the Her-
rings. The Indian genera are : —

(1) Alepoeephalus, which also occurs in the Atlantic
and Mediterranean : it has a scaly body but a scale-
less head : three species are found in Indian seas, at
240 to 902 fathoms :
10

74 -A Guide to the Zoological Collections

(2) Bathytroctes, which also occurs in the Atlantic :
two species live in Indian seas, at 500 to 740 fathoms :

(3) Narcetes, which differs from the two previous
genera only in dentition :

(4) Platytroctes, which has a curious high, compressed,
body, and no ventral fins: the same species P. apus
occurs in the Atlantic and in these seas :

(5) XenodermichthySy which occurs in the Atlantic and
in these seas at considerable depths : it has a black
scaleless skin, with minute luminous organs, and a
large eye :

(6) Leptoderma, which also occurs in the Atlantic : it
has a black scaleless skin with a luminous epidermis,
and an eye of enormous size.

(7 j Aulastomomorpha, which has the bones of the head
produced to form a tube-like snout, and the skin of the
head brilliantly phosphorescent.

Family XI. Notojrteridce [Cases 68-69].

This small family contains a single genus (Notoptcrus)
of fishes that inhabit freshwater of the Oriental and
West African regions. They are related to the Her-
rings. The two Indian species are known in Bengal as
Chitala and Phola.

Family XII. Halosauridce [Case 72].

This is a small family containing one genus, Halo-
saurus, the species of which are found only in the depths
of the Oceans. Five species occur in the seas of India,
at depths of 500 to 1000 fathoms. They have a long
tapering eel-like body, covered with scales, and in many
of the species the scales of the lateral line are enlarged
and grooved or perforated to lodge a luminous organ,

in the Fish Gallery of the Indian Museum. 75

Family XIII. Sy mbranchidce [Case 73].

The SymbrdnchidfB are freshwater eels, having neither
pectoral nor ventral fins and only vestiges of vertical
fins — thus, in external appearance, much resembling
snakes. The gill-openings are confluent, and one of the
Indian species has the gill-chamber produced to form a
respiratory sack for breathing air, somewhat after the
fashion of the Singhi fish. The curious geographical
distribution of the Sy mbranchidce has already been com-
mented on.

Family XIV. MuvamUlce [Cases 72-73].

The Eels are a very large family, of wide distribution.
Their body is snake-like, ventrals fins are never present,
pectoral fins are often wanting, and vertical fins are
sometimes quite rudimentary. They are abundant in
tropical seas, especially in the neighbourhood of coral
reefs, many inhabit the great depths of the sea, and
some are found in fresh water. The Indian species be-
long to the following genera : — Nemichthys (deep-sea),
Gavialiceps (deep-sea), Dysomma (deep-sea), Dysommopsis
(deep-sea), Synaphobranchus (deep-sea), Colocoiiger (deep-
sea), Congromurana (chiefly deep-sea), Uroconger (chiefly
deep-sea) , Promyllantor (deep-sea), Anguilla, MurcmesoXy
Saiiromnrmiesox (deep-sea), Saurenchelys (deep-sea),
Nettenchelys (deep-sea), Xenomystax (deep-sea), Miira?7i-
ichthys, Ophichthys, Moringua, Murccna and Gymno-
murcena.

Eels of the genus Murcena are particularly savage,
especially when breeding ; and I myself have several
times been attacked by them, when collecting on coral
reefs.

76 A Guide to the Zoological Collections

Suborder LOPHOBRANCHII [Case 75].

The gill-elements are not leaflets but little knobs, and
the gill-cover is a simple plate. The integument con-
sists of an armour of bony segments. The mouth is
situated at the end of a long tube-like snout. There is
no pneumatic duct to the air-bladder.

The Pipe-fishes of Indian seas fall into a single
family.

Family Syngnafhidce [Case 75].

This family includes the Pipe-fishes and Sea-horses.
These are marine, but generally live near shore, and
many of them find their way into brackish and fresh
water. Tiiey are all of small size, and are bad swimmers,
locomotion being chiefly effected by rapid vibrations of
the dorsal fin. In these fishes the male looks after the
eggs, which he carries about with him — either in a special
brood-pouch, or glued to the abdomen — until after they
are hatched. In Case 1 2 a male Hippocampus (Sea-horse)
is shown with the brood-pouch full of developing ova.

Most of the Indian genera, and even one species
[Hippocampus guttulatus) are also found in the Atlantic
and Mediterranean.

Suborder Plectognathi [Cases 74-75].

In this suborder of Bony-fishes the skin is usually
covered either with prickles and spines or with bony
plates, though it is sometimes naked. The ventral fins
are either absent or are reduced each to a spine, which
is sometimes large. A spinous dorsal fin is either
present or absent : when present the spines are few, but
the first one is often very large. The gills have the

in the Fish Gallery of the Indian Museum. 77

usual form, but the gill-openings are narrow slits. The
skeleton is incompletely ossified and the vertebrae are
few in number. There is no pneumatic duct to the air-
bladder. The suborder consists of two families.

Family I. Sclerodermi [Cases 74-75].

In this family there are distinct teeth in the jaws,
there is generally a spinous dorsal fin, and the ventral
fins are generally represented by a pair of spines. It is
divided into three subfamily groups : —

1. Subfamily Triacanthina, of which three Indian
genera are known, namely Triacanthus, which is a shore
fish, and TriacantJwdes and Haiimochirurgus which
belong to the deep-sea. Haiimochirurgus has the snout
produced to form a long tubular beak. In all the mem-
bers of this subfamily the skin is covered with small
prickly scales, there is a spinous dorsal fin, and a pair of
very strong ventral spines which can be erected and
fixed like bayonets.

2. Subfamily Balistimz, of which three genera are
known, all being represented in Indian Seas. They are
Batistes, known as File-fishes, or Trigger- fishes, the
species of which are very numerous round coral-reefs ;
Monacanthus of which the species are abundant among
coral-reefs but often also take to the open sea, swimm-
ing chiefly by rapid vibrations of the soft dorsal fin ;
and Anacanthus, which resembles Monacanthus in form
and habit, but has a barbel at the chin. The members
of this subfamily have strong chisel-like teeth with
which they bite off the pieces of coral and chip open the
mollusks upon which they feed : their skin is covered
either with granules or with hard rough bony scales,
and the ventral spines are rudimentary or absent. Both
Batistes and Monacanthus are also found in the tropical

78 A Guide to the Zoological Collections

parts of the Atlantic, Batistes being also represented in
the Mediterranean. One species of this genus, Batistes
maculatus, is found in the West Indian region, in the
Oriental region, and in Japan.

3. Subfamily Ostracionina. In the Box-fishes, which
include the single genus Ostracion, the body is angular
and the integument forms a firm carapace of immovable
bony plates, from which the end of the tail projects.
There are no ventral fins. The species of Ostracion
occur in all tropical seas and two species are also found
in the Mediterranean.

Family II. Gymnodontes [Cases 74-75].

In the family of Globe-fishes the bones of the jaws
form a beak something like that of a parrot, eminently
adapted for crushing the coral and mollusks on which
these fish feed, and there are neither spinous dorsal nor
ventral fins. The family is divided into three subfamilies
all of which are represented in India.

1. Subfamily Triodontincs : contains the single genus
and species Triodon bursarius in which the upper valve of
the " beak " is divided into two halves by a median
suture : it inhabits the Indian Ocean and Archipelago.
Like the members of the next subfamily it can distend
its abdomen with air. The skin is covered with rough
scutes.

2. Subfamily Tetrodontince : contains the Indian genera
Xenopterus and Tetrodon in which both jaws are cleft in
the middle line by a suture, and Diodon and Cliilomycterus
in which neither of the jaws are so cleft. Most of the
species are marine, but Xenopterus and several species
of Tetrodon enter estuaries and ascend into fresh water.
The skin, though often naked, is usually more or less
spiny or spicular, and in Diodon and Chiloinycterus the

in the Fish Gallery of the Indian Museum. 70.

spines are so numerous and so strong as to resemble
those of a hedgehog. All the Tetrodonts can inflate
their gullet, and so their abdominal cavity, like a balloon,
and many of them can make a croaking sound. Both
Tetrodon and Diodon occur in the Atlantic and Mediter-
ranean as well as in the Indian and Pacific Oceans,
and one species Diodon hysirix is common to all these
regions. Chilomycterus belongs to the Atlantic and the
Indo-Pacific.

3. Subfamily Molina. The Sun-fishes have a most
singularly abbreviated, round or oval, disk-like body.
They are pelagic fish and occur in all tropical and
temperate seas, and they grow to a great size. One
species is said to occur in Indian waters. The jaws of
the Sun-fish, like those of the Triacanthines, are weak.

Order II. GANOIDEI [Cases 26-29].

The second order of the Subclass Teleostomi contains
the Ganoid fishes, bat as none of these fishes are known
to occur in India we shall postpone their consideration :
moreover, their position in the Class of Fishes will be
better understood after we have considered the subclass
Chondropterygii. It will be sufficient, for the present, to
say that the Ganoids, in a general way, are remote
cousins to the Sharks and are the ancestors of the Bony
fishes, and that they are therefore, in this sense, inter-
mediate between the Teleostei and the Chondropterygii.

Subclass CHONDROPTERYGII [Cases 30-41].

This subclass contains the Sharks, Rays and Chi-
meeras, of which the first two groups are well represent-
ed in the seas and estuaries of India.

80 A Guide to the Zoological Collections

The skeleton is cartilaginous, though calcification
may sometimes occur in parts of it, and the tail is usual-
ly heterocercal : the gills are attached to the skin by
their outer margins, so that — with the exceptions to be
noted — there are as many external as internal gill-open-
ings and no gill-cover : there is a muscular conus arterio-
sus (see Case 10), with many valves, at the base of the
aorta : the mucous membrane of the intestine forms a
spiral valve (see Case 10) : the optic nerves do not simply
cross each other : impregnation is internal, and though
eggs may be laid the young are often born alive
(see Case 12): the ventral fins are placed far behind
the pectoral fins : the skin may be naked, but more
commonly it bears placoid scales, or granules or spines,
which last are sometimes hardly distinguishable from
small teeth. Geologically, the Chondropterygii are a
very ancient order : " some of the earliest determinable
fish remains are believed to be, or are, derived from
Plagiostomes " (Giinther).

Order I. PLAGIOSTOMA.

This Order is divided into two sections which grade
into one another, namely : (1) the Sharks [Selachoidei] in
which the gill-openings are lateral and the trunk gradu-
ally shades into the tail, and (2) the Rays (Baioidei), in
which the gill-openings are on the ventral surface and
the trunk is more or less disk-like.

Selachoidei (Sharks).

Six of the nine existing families of Sharks are repre-
sented in Indian Seas.

Family I. Car char iidce [Cases 39-41].
These are the true Sharks, known of all. The eye
has a nictitating membrane. They are common in all

in the Fish Gallery of the Indian Museum. 81

seas. Carcharias gangeticus is the Shark that comes up
the Hooghly in the hot weather and attacks bathers at
the Calcutta ghats. Zygoma is the Hammerhead Shark,
of which two of the Indian species are also found in the
Atlantic and Mediterranean. An unborn young of
Zygoma blochii, with the placenta and curious placental
cord attached, is shown in Case 12.

Family II. Lamnidce.

These are also large and formidable Sharks, found in
all seas. There is no nictitating membrane to the eye :
the first dorsal fin stands above the space between the
pectoral and ventral fins. Lamna spallanzanii and
Alopecias vulpes are found in the Atlantic and Mediter-
ranean as well as in Indian seas.

Family III. Rhiiiodontldce,

This family contains a single species, Rhinodon typicus,
found only in the Indian Ocean, and growing to a
gigantic size — seventy feet, it is said. The snout is
broad, short and flat, and the mouth is singularly situa-
ted at the end of it. Its teeth are very small and it is
harmless.

Family IV. 'Notidanidce.

A small family containing the single genus Notidanus,
with four species, three of which belong to the Mediter-
ranean and Atlantic, while the fourth, Notidanus indicus,
is found in the Indian and Pacific Oceans. This Indian
shark can be recognized by its gill-openings, which are
seven in number, instead of the usual five, and by the
single dorsal fin. Notidanus is said to reach a length of
about fifteen feet.
ii

82 A Guide to the Zoological Collecliofis

Family V. Scylliiclce [Case 38].

The Dog-fishes have no nictitating- membrane, and
their first dorsal fin is placed far back, above or behind
the ventral fins. They are usually of small size and are
not dangerous to man : they live chiefly on mollusks and
crustaceans. The genera found in India are Scyllium,
which occurs in all seas; Ginglymostoma, which also
occurs in the Atlantic and the Red Sea ; and Chiloscyllium
and Stegostoma, which are restricted to the Indian and
Western Pacific Oceans. Stegostoma is the " Tiger-
shark," a common Indian form, which grows to a length
of 10 or 15 feet. Ginglymostoma also grows to a large
size.

Family VI. Spincwidce [Case 37].

The Spiny Dog-fishes of these seas are recognized by
the presence of a spine at the fore end of each dorsal fin.
Only two Indian species are known, namely, (1) Centro-
phorus Rossi from 430 fathoms, and (2) Centroscyllium
ornatum from 285 to 690 fathoms. Other species of
Centrophorus are found in the Atlantic and Mediter-
ranean, and of Centroscyllium near Arctic and Antarctic
seas.

Batoidei (Rays).
All of the six known families of Rays are represented
in Indian Seas.

Family I. Vvistidce [Cases 36-37J.

The Saw-fishes resemble Sharks in form of body, but
the gill-openings are like those of the Rays in being on
the ventral surface. The snout is produced to form a
long narrow flat blade, which is armed with strong teeth
along both edges and is a formidable weapon of offence.
Saw-fishes grow to a length of 20 feet. Of the four

in the Fish Gallery of the Indian Museum. 83

known Indian species two occur in the Atlantic, one of
these being also found in the Mediterranean.

Family II. Bhinobatidce [Cases 35-36].

In this family the form of the body is still Shark -like,
but the broadening- of the pectoral regions, which is so
characteristic of the Rays, is becoming manifest. The
snout is produced, but not nearly to such an extent as it
is in the Saw-fishes,, and it has no teeth on the edges.
Of the six known Indian species two, namely, Rhinobatus
halavi and R. columns, also occur in the Atlantic and
Alediterranean.

Family III. Torpcdinidce [Case 33].

In this family the form of the body is rather more
Ray-like than Shark-like, the pectoral region being
much broadened to form a disk, from which however the
tail is not yet sharply delimited. On either side of the
disk, between the head and the pectoral fins, is an
" electric organ," the shock from which can disable
enemies and, perhaps, can also overcome prey. A dis-
section of the electric organ of one of the Indian species
is shown in Case 11 : it is seen to consist of a multitude
of vertically-placed hexagonal prisms, and to be supplied
by several enormous nerve-trunks. Three Indian species
of Electric Rays are known, namely, Narcine ttmlei and
Astrape dipterygia from shallow water, and Benthobatis
moresbyi from 430 fathoms. The skin of the Electric
Rays is quite smooth.

Family IV. Rajidce [Case 34].

In the true Rays the head, trunk, and pectoral fins
together form a broad flat disk, from which the tail is
sharply marked off. The skin may be almost smooth,
but is more often furnished with prickles and definitely-

84 A Guide to the Zoological Collcctiotis

placed spines— these being more numerous in the female.
The Rays live on the sea-bottom and progress by the
undulations of their pectoral fins. The genera that are
found in Indian Seas are Raja and Plalyrhina. The
Indian species of Raja, three in number, are only found
in deep water.

Family V. Trygonidce [Case 34].

The Sting-rays have a disk-like body and a long lash-
like tail, which is even more sharply demarcated from
the disk than is that of the true Rays. Moreover, near
the base of the tail, in many species, there exists a great
erectile barbed spine, which is capable of inflicting a
severe and even dangerous wound. The spine is shed
and replaced by reserve spines, like the poison fang of
a snake. The Sting-rays, like the true Rays and Electric
Rays, live on the bottom : they have pavement-like
crushing-teeth for feeding on hard-shelled mollusks and
crustaceans. They are particularly numerous in the
muddy water at the mouths of estuaries, and, like so
many fishes that have this habitat, they have a tendency
to spread up the estuaries into freshwater and so, in some
cases, to become incorporated in the freshwater fauna.
Many. Try gons bring forth their young alive, the embryo
being nourished during its development, not by a vas-
cular placenta, but by a milk-like secretion which is
poured forth from a multitude of special glands in the
uterine mucous membrane and finds its way into the gullet
of the embryo through the latter's spiracles. Speci-
mens in Case 12 illustrate this singular method of intra-
uterine nutrition. Two species of Trygon, T. bennettii
and T. pastinaca, are common to the Atlantic and Indo-
Pacific, the latter also being found in the Mediterranean.
Pteroplatcea also is found both in the Atlantic and in the

in the Fish Gallery of the Indian Museum. 85

Indo-Pacific. Some of the Trygons grow to an enor-
mous size.

Family VI. 3fi/liobatidce [Case 33].

The Eagle-rays or Sea-devils chiefly differ from the
Trygons in having a thicker disk and a slightly differ-
ent arrangement of the pectoral fins, which are more
extended laterally and less extended forwards.

In their mode of life they much resemble the Trygons,
and have a pavement-like arrangement of crushing-teeth
even more perfect than that of the Trygons. Some of
them resemble the Trygons in their mode of bringing
forth their young. Some of them grow to an enormous
size. All the four Indian genera of Eagle-rays also
occur in the Mediterranean and Atlantic.

Order II. HOLOCEPHALA [Cases 30-32].

Of all the members of the subclass Chondropterygii,
the Holocephala, or Chimaeras, make the nearest approach
to the Ganoids. They differ from all other members of
their subclass, and resemble the Ganoids and their des-
cendants, in having a gill-cover and so only a single
external gill-opening on each side. But the gill-cover
is a rudimentary one, and merely covers the four exter-
nal gill-clefts, which resemble those of sharks : it does
not cover a gill-chamber in which the gills lie free. Ex-
cept in this respect and in certain skeletal characters,
the Chimaeras agree with the Sharks. The males have
a singular erectile appendage on top of the head.

No actual specimens of Chimcera and Callorhynchus
(the two genera that now constitute the Order) have been
taken in Indian seas, but their empty egg-capsules have
been dredged in the Bay of Bengal between 400 and 600
fathoms, so that specimens may be discovered any day.

86 A Guide to the Zoological Collections

We have next to consider, but more briefly, certain
Orders of fishes that are not represented in India. They
are the Ganoids and the Dipnoi.

Ganoid Fishes [Cases 26-29].

To the Order of Ganoids " belong- the majority of the
fossil fish-remains of palaeozoic and mesozoic age, whilst
it is very scantily represented in the recent fauna and
evidently verging- on total extinction." [Gunther).

Most of the Ganoids live in fresh water ; some species
of Sturgeons alone are found in the sea, but even they
ascend rivers at the spawning season. Their Geographi-
cal Distribution is shown in the coloured map in Case 29,
from which it will be seen that none occur in India, al-
though some are found in Central Asia and China.

The Ganoids are, in a way, intermediate between the
Bony-fishes and the Chondropterygii. As in the Sharks,
the intestine has a spiral valve, though it may be rudi-
mentary; the bulb of the aorta is muscular, and is pro-
vided with numerous valves; and the tail is commonly,
though not always, heterocercal. As in the Bony-fishes,
the gills are free and lie in a common gill-chamber on
each side of the head — the gill-chamber being protected
by a gill-cover and communicating with the exterior by a
single opening. As in many Physostomous Bony-fishes,
there is an air-bladder with a pneumatic duct. The
skeleton may be cartilaginous and of the Chimcera type,
or it may be bony. There are vertical and paired fins,
and the ventral fins, when present, are placed far behind
the pectorals. The scales may be either cycloid or ganoid.

The specimens in Cases 26-29 are merely meant to
give a general idea of the Order. Accipenser comes
nearest to the Chimaeras, Amia comes nearest to the
Bony-fishes.

in the Fish Gallery of the Indian Museum. 87

Subclass DIPNOI [Cases 23-25].

From the map in this Case, showing the Geographi-
cal Distribution of this small subclass of Fishes it will
be seen that none occur in Asia and none north of the
tropic-;. As a matter of fact, they are now restricted to
the fresh waters of tropical and subtropical latitudes in
South America, Africa, and Australia.

They differ from all other fishes, and approach Amphi-
bia, in having (1) an air-bladder that functions as a true
lung, and (2) an incipient pulmonary circulation. They
are further remarkable among fishes in the form of their
paired fins, which have a segmented axis foreshadowing
the segmented limbs of higher vertebrates.

The skeleton is partly cartilaginous and partly bony,
and, as in the Sharks, the intestine has a spiral valve
and opens into a cloaca.

The gills resemble those of Teleosteans and Ganoids
in lying free within a gill-chamber on either side of the
head. The gill-chamber has a gill-cover, though a
rudimentary one — and opens to the exterior by a single
gill-opening.

The body is covered with cyloid scales.

By means of their lung the Dipnoi can live in water
that is too impure for branchial respiration.

The subclass is represented in this Gallery by a stuffed
specimen, a dissected pectoral fin, and a skull, of Cerato-
dus. In the skull notice the curious compound teeth.
Similar teeth have been found, fossil, in Secondary strata
in India and Europe.

The Dipnoi are generally regarded as a divergent
branch of the stock from which the Ganoids descended..
They are also connected, through the ancestors of the-
Chimseras, with the Chondropterygian stock.

88 A Guide to the Zoological Collections i?i the Fish Gallery.

Characteristic Fishes of the Deep Sea.

In Cases 15-20 are exhibited specimens of some fishes
that are specially adapted for life under the peculiar
conditions that prevail in the depths of the sea.

In Case 15 are specimens of fishes that, in all pro-
bability, live in constant darkness or gloom. The eyes
show marked degeneration, but, so far as is known,
there is no compensating overgrowth of any of the other
organs of sense.

In Case 16 are specimens of fishes that undoubtedly
live at the bottom, in depths to which no daylight
penetrates. The eyes are completely-hidden rudiments,
but, so far as is known, there is no compensating over-
growth of any of the other organs of sense.

In Case 17 are specimens of fishes that live in dark-
ness and have very degenerate eyes, but have the sense
of touch greatly developed in compensation.

In Case 18 are specimens of fishes that undoubtedly
live at depths to which little, if any, daylight reaches.
Their eyes are of enormous size to catch such light —
whether faint gleams of daylight or phosphorescent
light — as does exist.

In Case 19 are specimens of fishes that live in con-
stant darkness or gloom, but possess their own indepen-
dent means of illumination.

In Case 20 are specimens that illustrate in an extreme
degree the extraordinary rapacity and voracity of certain
deep-sea fishes.

INDEX.

Page.

Page.

Page.

Acanthopterygii .

• 42

Batrachidae

..

53

Cirrhitidse .

. 44

Acronnridae

- 49

Bekti

>.

42

Climbing-perch

• 59

Air-bladder

. 28

Berycidae

• .

46

Clupeidae ,

• 72

Alepocephalidas .

. 73

Bleekeria

•

64

Cod-fishes .

. 6r

Alepocephalus

• 73

Blennies

.

57

Coryphsenidce .

. 5i

Amphioxus

. 9

Blenniidae

•

57

Cottidae

♦ 55

Anacanthini

. 61

"Bombay Duck" .

.

68

Cyclostoma

11

,, Gadoide

1 61

Box-fishes

.

78

Cyprinidag .

. 70

,, Pleuro-

Breathing-organs

.

25

Cyprinodontidas .

. 7i

nectoide

i °5

Brotula ,

•

62

Cyttidaj

• 5i

Anchovy

• 72

Bu?nnialo

.

68

Antennarius

• 53

Ascidiacea, com

-

pound

. 8

Ascidian, simp]

fixed .

. 5

Ateleopodidoe .

. 65

Atherinidse .

. 58

Deep- Sea fauna

• 38

Aulastomomorpha

74

Carangidae

50

Dermatorus

. 63

Carchariidae

80

Dibranchus .

• 55

Carps

70

Dicrolene .

. 63

Cataphracti

56

Digestive system .

. 24

Cat-fishes

67

Dinematichthys .

. 62

Centriscida?

59

Diplacanthopoma .

• 63

Cepolidae

57

Dipnoi

86, 87

Ceratias

54

Dog-fishes ,

. 82

Balanoglossus

2

Characteristic Dei

-P

Dolphins

• 51

Balistinae

• 77

Sea fishes

88

Dories

• 5°

Bammi

• 57

Chaunax

55

Dragonets

. 56

Band-fishes

• 57

Chimaeras

79

•85

Bassozetus

• 63

Chirocentridae

73

Bathyclupea .

. 46

Chitala

• •

74

Bathypterois

. 69

Chlorophthalmus

• •

69

Bathytroctes

- 74

Chondropteryjjii

• •

79

Batoidei

So, 82

Chromides

. .

61

. -

9o

Index.

Page.

Page.

Page.

Gold-fish

.. 70

Echeneis

• • 52

Gonchi

• • 57

Eels

.. 75

Grey mullets

• • 58

Electric organs

• • 32

Gurnards

• • 55

Electric Rays

.. 83

Gymnodontes

.. 78

Labridse

Labyrinthici .
Lamnidae
Lampreys
Lamprogrammus .
Lancelets
Larvacea
Leptoderma

. 60

. 59
. 81
. 11
. 63
. 9
. 8

■ 74

Fierasfer

.. 64

Habits of fishes

• • 35

Loaches .

. 70

File- fishes

.. 77

Hag-fishes

.. 11

Lophius .

. 54

Fishing-Frogs

.. 53

Hairtails

.. 49

Lophobranchii

• 76

Fistularidae

.. 58

Halicmetus

• • 55

Flat-fishes

61,65

Halieutaea

• • 55

Flying-fishes

.. 7i

Halosauridas

.. 74

Form of the body . . 15

Hammer-head shark 81

Freshwater eels

-. 75

Harpodon

.. 69

Frog-fishes

•• 53

Heart
Hephthocara

.. 25
.. 64

Herrings

.. 72

Mackerels

• 5i

Hilsa

67, 73

Macruridae .

. 64

Holocentrum

.. 47

Mahseer

• 7o

Holocephala

.. 85

Mailed Gurnards .

• 55

Hoplostethus

.. 46

Malacanthidas

• 53

Horse-Mackerels

.. 5°

Malthopsis

• 55

Gadidae

.. 62

Mango fish

• 47

Gadoidei

.. 61

Mastacembelidsa .

• 57

Ganoidei

79,86

Melamphaes .

• 47

Gar-piUes

.. 71

Molinae

• 79

Geographical

rela-

Monocentris

. 46

tions, fresh

water

Mugilidae

. 58

fishes

•• 35

Mullidae

. 44

Geographical

rela-

Kidneys

.. 29

Muraenidae

• 75

tions, marine

ishes 37

Koi

.. 59

Murral

• 59

Globe-fishes

.. 78

Kurtidae

.. 47

Muscular system .

• 32

Glyphidodontidae . . 60

Myliobatidae

• 85

Glyptophidium

•• 63

Myripristis

• 47

Gobiidae

.. 5*

Index.

9i

Page.

Pa

Se-

Page.

Pleuronectidae

61,

65

Scopelidoe

.. 68

Polymixia

..

47

Scopelus

.. 69

Polynemidae

• •

47

Scorpaenidse

.. 44

Pomfrets

« •

5i

Scylliidae

.. 82

Pristidae

82

Sea-breams
Sea-devils

.. 44
.. 85

Nandidae

45

Sea-horses

.. 76

Narcetes . .

74

Sea-perch

•• 45

Neobythites

62

Sea-squirts

•• 3

Neoscopelus

69

Seer-fish

.. 5i

Nervous system

30

Selachoidei

.. 80

Notidanidaa

81

Sharks

79, 80

Notopteridae

74

Rajidse

• *

83

Silli fish

.. 48

Rays 79

, 80

, 82

Siluridas

.. 67

Red Mullets

• •

44

Skeleton

.. 20

Remora

• •

52

Skin

.. 18

Reproduction

• •

32

Sparidae

.. 44

Rhinobatidae

• •

83

Sphyraenidae

• • 57

Rhinodontidce

• •

81

Spinacidae

.. 82

Ribbon-fishes

..

60

Spiny Dog-fishes

.. 82

Odontostomus

• 70

Ruhu

67

Spiny-eels

•• 57

Onirodes

• 54

Squamipinnes

•• 43

Ophidiidae

. 62

Sternoptychidae

■• 7i

Ophiocephalidae .

• 59

Sting-rays

.. 84

Ostracionina

• 78

Stomiatidae
Stromateidae
Sturgeons
Sucker-fish

.. 72

•• 5i

.. 86
.. 52

Saccogaster

••

64

Sun-fish

.. 79

Sand-eels

••

64

Surgeon-fishes

.. 49

Saurida

• •

69

Swim-bladder

.. 28

Saurus

••

69

Sword-fishes

.. 48

Pediculati

• 53

Saw-fishes

••

82

Symbranchidae

• • 75

Perches

. 42

Scabbard-fishes

••

49

Syngnathidae

.. 7b

Percidae

• 42

Sciaenidae

• •

48

Phola

• • 74

Sclerodermi

. .

77

Pilot-fish

.. 50

Scombresocidae

a ,

7i

Pipe-fishes

.. 76

Scombridas

• •

5i

Plagiostoma

.. 8c

Scopelarchus

68

Platytroctes

• • 74

Scopelengys

.

7c

Plectognathi

• • 7*

92

Index

Page.

Page.

Page.

"1

ft

Tauredophidium

63

TriodontiDae

.. 78

Teleostei

. .

42

Trygonidae

.. 84

Teleostomi

42

79

Trygons

.. 84

Wrasses

.. 60

Tengra

• •

67

Tube-fishes

.. 58

Tetrodontinae

. .

78

Tunicata

.. 3

Teuthididae

. ,

45

Thaliacea

• •

8

Tiger-shark

. ■

82

Topography of

the

body

t ,

17

Topsi

47

Xenodermichthys

.. 74

Torpedinidse

83

Xiphiidae

.. 48

Trachichthys

46

Uses of fishes

.. 35

Trachinidae

• *

52

Trachypteridae

60

Triacanthinae

77

Trichonotidae

. .

57

Trigger-fishes

. •

77

List of Publications issued by the Trustees of the

Indian Museum.

Rs. As. P.

Account of the Deep-Sea Brachyura collected by the
R.I. M.S. Investigator. By A. Alcock, M.B., G.M.Z.S.,
F.G.S. .. .. .. .. ..600

Account of the Deep-Sea Madreporaria collected by the
R.I. M.S. Investigator. By A. Alcock, M.B., CM Z.S.,
F.G.S. .. .. .. .. ..400

Catalogue of Archaeological Collections in the Indian
Museum, Parts I and II. By J. Anderson, M.D.,
F.R.S., etc. .. .. .. .. 4 12 0

Catalogue of Coins of the Indian Museum, Parts I to IV.

By C. J. Rodgers, M.R.A.S., M.N.S. .. . . 24 0 0

Catalogue of Indian Deep-Sea Fishes in the Indian

Museum. By A. Alcock, M.B., CM. Z.S., F.G.S. .. 5 0 0

Catalogue of Mammalia in the Indian Museum, Part I.
By J. Anderson, M.D., F.R.S., Part II. By W. L.
Sclater, M.A., F.Z.S. .. .. . . 6 0 Q

Catalogue of Mantodea in the Indian Museum, Parts I

and II. By J. Wood-Mason, F.Z.S. , etc. .. .. 2 0 0

Catalogue of Moths of India, Parts I to VII. By E. C

Cotes and C Swinhoe, F.L S., F.Z S., etc. . . 5 12 0

Echinoderma of the Indian Museum : Deep-Sea Ophiu-
roidea collected by the R I. M.S. Investigator. By R.
Koehler . . . . . . . . .'. " 10 0 0

Figures and Descriptions of Nine Species of Squillida:
from the Collection in the Indian Museum. By J.
Wood-Mason, F.Z.S., etc. Edited by A. Alcock, M.B.,
CM Z.S., F.G.S. .. .. .. .200

Guide to the Zoological Collections exhibited in the Fish
Gallery of the Indian Museum. By A. Alcock, M.B.,
C.M.Z.S., F.G.S. .. .. .. .. 0 8 0

Guide to the Zoological Collections exhibited in the Inver-
tebrate Gallery of the Indian Museum. By A. Alcock,
M.B., C M.Z S., F.G.S. .. .. .. 0 10 0

Guide to the Zoological Collections exhibited in the
Reptile and Amphibia Gallery of the Indian Museum.
By A. Alcock, M.B., C M.Z. S., F.G.S. .. ..-0 3 0

Rs. As P.
Hand List of Mollusca in the Indian Museum, Parts I,

II, and Fasciculus E. By G. Nevill, C.M.Z.S., etc.

Index, Parts I and II. By W. Theobald . . ..740

List of Batrachia in the Indian Museum. By W. L.

Sclater, M.A., F.Z.S. . . .'. ..100

List of Snakes in the Indian Museum. By W. L. Sclater,

M.A., F.Z.S. .. .. .. ..100

Monograph of the Asiatic Chiroptera and Catalogue of

the Species of Bats in the Indian Museum. By G. E.

Dobson, M.A., M.B., F.R.S., etc. .. ..300

£ s. d.

Monograph of the Oriental Cicadidas, Parts I to VII.

By W. L. Distant, F.E.S. .. ... ..22 6

The above can be obtained from the Superintendent of the
Indian Museum, Calcutta, and from Messrs. Friedlander & Son,
11, Carlstrasse, Berlin.

Other Publications sold by the Superintendent of the Indian
Museum (also obtainable from Messrs. Friedlander & Son).

Issued by the Director of the Royal Indian Marine.

Rs. As. P.

Illustrations of the Zoology of the R.I.M.S. Investigator,
1892. Fishes, Plates i-vii. Crustacea Plates

i-v. .. .. .. 12 0 0

1894. Fishes, Plates viii-xiii. Crustacea.
Plates vi-viii. Echinoderma, Plates
i-iii. .. .. .. 12 0 <>

,, 189.r). Echinoderma, Plates iv-v. Fishes,

Plates xiv-xvi. Crustacea. Plates
ix-xv. . . . . 12 0 0

1896. Crustacea, Plates xvi-xxvii. .. 12 0 «>

1897. Fishes, Plate xvii. Crustacea, Plates

xxviii-xxxii. Mollusca, Plates i-vi. . . 12 0 0

1898. Fishes, Plates xviii-xxiv. Crustacea,

Plates xxxiii-xxxv. Mollusca, Plates

vii-viii. .. . . . . 12 0 0

1899. Fishes, Plates xxv-xxvi. Crustacea,

Plates xxxvi-xlv. . . . . 12 0 0

QL618 A4 1899
\ guide i" tin HxJogical collcctio
Harvard MCZ Library

3 2044 062 423 751

JfliP