Chapter XXI: The Fishes of the Deep Sea (6)

About forty species of “Gurnards” are known from tropical and temperate zones. They are too well known to need detailed description; one of their principal characteristics is the three free finger-like pectoral appendages, which serve as organs of locomotion as well as touch, and which are supplied with strong nerves, as noticed above (pp. 108 and 120). The fins are frequently beautifully ornamented, especially the inner side of the long and broad pectorals, which is most exposed to the light when the fish is floating on the surface of the water, with pectorals spread out like wings. The grunting noise made by Gurnards when taken out of the water is caused by the escape of gas from the air-bladder through the open pneumatic duct. Gurnards are generally used as food; seven species occur on the British coast: the Red Gurnard (_T. pini_), the Streaked Gurnard (_T. lineata_), the Sapphirine Gurnard (_T. hirundo_), the Grey Gurnard (_T. gurnardus_), Bloch’s Gurnard (_T. cuculus_), the Piper (_T. lyra_), and the Long-finned Gurnard (_T. obscura_ or _T. lucerna_). Singularly, the European species cross the Atlantic but rarely, the American species belonging chiefly to the division _Prionotus_.

Several other genera belong to this family; for completeness’ sake they are mentioned here, viz. _Bunocottus_ from Cape Horn; _Rhamphocottus_, _Triglops_ from Arctic North America; _Podabrus_, _Blepsias_, _Nautichthys_, _Scorpænichthys_, _Hemilepidotus_, _Artedius_, from the North Pacific; _Ptyonotus_, from Lake Ontario; _Polycaulus_ from Indian Seas; Bembras from the Japanese Sea.

FOURTEENTH FAMILY--CATAPHRACTI.

_Form of the body elongate, sub-cylindrical. Dentition feeble. Body completely cuirassed with osseous keeled scales or plates. A bony stay connects the angle of the præoperculum with the infraorbital ring. Ventrals thoracic._

Marine fishes, and partly pelagic. _Petalopteryx_, from the chalk of Mount Lebanon, is supposed to have a resemblance to _Dactylopterus_.

AGONUS.--Head and body angular, covered with bony plates. Two
dorsal fins; no pectoral appendages. Small teeth in the jaws.

Small fishes, from the northern parts of the temperate zone and extending into the Arctic Ocean; the genus reappears in the Southern Hemisphere on the coast of Chile. Of the eleven species known, one (_A. cataphractus_) is not uncommon on the coast of Great Britain.

ASPIDOPHOROIDES, from Greenland, has a very similar form of the
body, but possesses one short dorsal fin only.

SIPHAGONUS.--With the snout produced into a long tube like a
Syngnathus; chin prominent, with a barbel.

From Behring’s Strait and Japan.

PERISTETHUS.--Head parallelopiped, with the upper surface and
the sides entirely bony; each præorbital prolonged into a long
flat process, projecting beyond the snout. Body cuirassed with
large bony plates. One continuous dorsal, or two dorsals, of
which the second is the more developed. Two free pectoral
appendages. Teeth none; lower jaw with barbels.

Singularly shaped fishes, of rather small size, from the Mediterranean, the warmer parts of the Atlantic, and the Indian Ocean; of the ten species known one species only has been found in the Pacific, near the Sandwich Islands. The European species is _P. cataphractum_. They are not common, and probably inhabit greater depths than the Gurnards, with which they have much in common as regards their habits.

DACTYLOPTERUS.--Head parallelopiped, with the upper surface and
the sides entirely bony; scapula and angle of the præoperculum
produced into long spines. Body with strongly keeled scales of
moderate size; lateral line none. Two dorsal fins, the second
not much longer than the first; pectoral very long, an organ of
flying, with the upper portion detached and shorter. Granular
teeth in the jaws; none on the palate. Air-bladder divided into
two lateral halves, each with a larger muscle.

Of “Flying Gurnards” three species only are known, which are very abundant in the Mediterranean, the tropical Atlantic, and Indo-Pacific. They, and the Flying Herrings (Exocoetus), are the only fishes which are enabled by their long pectoral fins to take flying leaps out of the water, and deserve the name of “Flying-Fishes.” They are much heavier, and attain to a larger size, than the Exocoeti, specimens of eighteen inches in length not being scarce. When young, their pectorals are much shorter, and, consequently, they are unable to raise themselves out of the water (_Cephalacanthus_).

The vertebral column shows a singular coalescence of the anterior vertebræ, which form a simple tube, as in _Fistularia_.

* * * * *

WE insert here as an appendix to this division the small family of _Pegasidæ_, the natural affinities of which are not yet clearly understood, but which resembles in some of its characters the _Cataphracti_.

FIFTEENTH FAMILY--PEGASIDÆ.

_Body entirely covered with bony plates, anchylosed on the trunk and movable on the tail. Barbels none. The margin of the upper jaw is formed by the intermaxillaries and their cutaneous prolongation, which extends downwards to the extremity of the maxillaries. Gill-cover formed by a large plate, homologous to the operculum, præoperculum, and sub-operculum; interoperculum a long fine bone, hidden below the gill-plate. One rudimentary branchiostegal. The gill-plate is united with the isthmus by a narrow membrane; gill-openings narrow, in front of the base of the pectoral fin. Gills four, lamellated. Pseudobranchiæ and air-bladder absent. One short dorsal and anal fin, opposite to each other. Ventral fin present. Ovarian sacs closed._

One genus only is known, _Pegasus_. Its pectoral fins are broad, horizontal, long, composed of simple rays, some of which are sometimes spinous. Ventral fins one- or two-rayed. Upper part of the snout produced into a shorter or longer process. Mouth inferior, toothless. Suborbital ring well developed, forming a suture with the gill-cover. Vertebræ in small number, thin; no ribs. Four species are known, two of which are of a shorter, and the two others of a longer form. The former are _P. draconis_, common in the Indian Ocean, and _P. volans_, which is frequently stuck by the Chinese into the insect-boxes which they manufacture for sale. The two elongate species, _P. natans_ and _P. lancifer_, are from the Chinese and Australian coasts. They are all very small fishes, probably living on sandy shoal places near the coast.

NINTH DIVISION--ACANTHOPTERYGII GOBIIFORMES.

_The spinous dorsal, or spinous portion of the dorsal is always present, short, either composed of flexible spines, or much less developed than the soft; the soft dorsal and anal of equal extent. No bony stay for the angle of the præoperculum. Ventrals thoracic or jugular, if present, composed of one spine and five, rarely four, soft rays. A prominent anal papilla._

Shore-fishes, mostly exclusively marine, but some entering and living in fresh waters.

FIRST FAMILY--DISCOBOLI.

_Body thick or oblong, naked or tubercular. Teeth small. Ventral fins with one spine and five rays, all being rudimentary and forming the osseous support of a round disk, which is surrounded by a cutaneous fringe. Gill-openings narrow, the gill-membranes being attached to the isthmus._

Carnivorous fishes, living at the bottom of the shores of northern seas. By their ventral disk they are enabled to attach themselves very firmly to rocks.

CYCLOPTERUS.--Body thick, short, covered with a viscous,
tubercular skin. Head large, snout short. Villiform teeth in the
jaws, none on the palate. Skeleton soft, with but little earthy
matter.

Three species of “Lump-suckers” are known from the northern temperate and the arctic zones. The common North European and North American species, _C. lumpus_, is known also by the names of “Cock- and Hen-Paddle.” It attains to a length of twenty-four inches, but generally is much smaller. It is difficult to remove it from any object to which it once has attached itself by means of its sucking-disk. Its skin is so thick as to more or less entirely conceal the first dorsal fin; it is covered with rough tubercles, the larger ones being arranged in four series along each side of the body. In young specimens these tubercles are absent. The arctic species, _C. spinosus_, has large conical plates on the head and body, each plate with a spine in the centre. Also of this species the young are naked, the plates making only gradually their appearance, in the form of groups of tubercles. Their development is irregular, as young specimens of the same size may be entirely naked or tubercular. This species ranges beyond the 81° lat. N.

LIPARIS.--Body sub-cylindrical, enveloped in a more or less
loose naked skin; head broad, obtuse. The infraorbital bone is
styliform posteriorly, extending backwards to the margin of
the præoperculum. One dorsal fin, with feeble flexible rays.
Villiform teeth in the jaws, none on the palate.

Small fishes from the northern coasts of the temperate zone, ranging beyond the arctic circle. Eight species are known, of which two (_L. lineatus_ and _L. montagui_) occur on the British coasts.

SECOND FAMILY--GOBIIDÆ.

_Body elongate, naked or scaly. Teeth generally small, sometimes with canines. The spinous dorsal fin, or portion of the dorsal fin, is the less developed, and composed of flexible spines; anal similarly developed as the soft dorsal. Sometimes the ventrals are united into a disk. Gill-opening more or less narrow, the gill-membranes being attached to the isthmus._

Small carnivorous littoral fishes, many of which have become acclimatised in fresh water. They are very abundant with regard to species as well as individuals, and found on or near the coasts of all temperate and tropical regions. Geologically they appear first in the chalk.

GOBIUS.--Body scaly. Two dorsal fins, the anterior generally
with six flexible spines. Ventral fins united, forming a disk
which is not attached to the abdomen. Gill-opening vertical,
moderately wide.

The “Gobies” are distributed over all temperate and tropical coasts, and abundant, especially on the latter. Nearly three hundred species have been described. They live especially on rocky coasts, attaching themselves firmly with their ventrals to a rock in almost any position, and thus withstanding the force of the waves. Many of the species seem to delight in darting from place to place in the rush of water which breaks upon the shore. Others live in quiet brackish water, and not a few have become entirely acclimatised in fresh water, especially lakes. The males of some species construct nests for the eggs, which they jealously watch, and defend even for some time after the young are hatched. Several species are found on the British coast: _G. niger_, _paganellus_, _auratus_, _minutus_, _ruthensparri_. Fossil species of this genus have been found at Monte Bolca.

A very small Goby, _Latrunculus pellucidus_, common in some localities of the British Islands and other parts of Europe, is distinguished by its transparent body, wide mouth, and uniserial dentition. According to R. Collett it offers some very remarkable peculiarities. It lives one year only, being the first instance of an _annual vertebrate_. It spawns in June and July, the eggs are hatched in August, and the fishes attain their full growth in the months from October to December. In this stage the sexes are quite alike, both having very small teeth and feeble jaws. In April the males lose the small teeth, which are replaced by very long and strong teeth, the jaws themselves becoming stronger. The teeth of the females remain unchanged. In July and August all the adults die off, and in September only the fry are to be found.

There are several other genera, closely allied to Gobius, as _Euctenogobius_, _Lophiogobius_, _Doliichthys_, _Apocryptes_, _Evorthodus_, _Gobiosoma_ and _Gobiodon_ (with scaleless body) _Triænophorichthys_.

SICYDIUM.--Body covered with ctenoid scales of rather small
size. Cleft of the mouth nearly horizontal, with the upper jaw
prominent; lips very thick; the lower lip generally with a
series of minute horny teeth. A series of numerous small teeth
in upper jaw, implanted in the gum, and generally movable;
the lower jaw with a series of conical widely-set teeth. Two
dorsal fins, the anterior with six flexible spines. Ventral fins
united, and forming a short disk, more or less adherent to the
abdomen.

Small freshwater fishes inhabiting the rivers and rivulets of the islands of the tropical Indo-Pacific. About twelve species are known; one occurs in the West Indies. _Lentipes_ from the Sandwich Islands is allied to _Sicydium_.

PERIOPHTHALMUS.--Body covered with ctenoid scales of small or
moderate size. Cleft of the mouth nearly horizontal, with the
upper jaw somewhat longer. Eyes very close together, immediately
below the upper profile, prominent, but retractile, with a
well-developed outer eyelid. Teeth conical, vertical in both
jaws. Two dorsal fins, the anterior with flexible spines; caudal
fin with the lower margin oblique; base of the pectoral fin
free, with strong muscles. Ventral fins more or less coalesced.
Gill-openings narrow.

The fishes of this genus, and the closely-allied _Boleophthalmus_, are exceedingly common on the coasts of the tropical Indo-Pacific, especially on parts covered with mud or fucus. During ebb they leave the water and hunt for small crustaceans, and other small animals disporting themselves on the ground which is left uncovered by the receding water. With the aid of their strong pectoral and ventral fins and their tail, they hop freely over the ground, and escape danger by rapid leaps. The peculiar construction of their eyes, which are very movable, and can be thrust far out of their sockets, enables them to see in the air as well as in the water; when the eyes are retracted they are protected by a membranous eyelid. These fishes are absent in the eastern parts of the Pacific and on the American side of the Atlantic; but singularly enough one species reappears on the West African coast. About seven species are known (including _Boleophthalmus_), _P. koelreuteri_ being one of the most common fishes of the Indian Ocean.

ELEOTRIS.--Body scaly; eyes of moderate size, lateral, not
prominent. Teeth small. Two dorsal fins, the anterior generally
with six spines. Ventrals not united, though close together,
with one spine and five rays.

About sixty species are known from the tropics, only a few extending into the temperate zone. As regards form, they repeat almost all the modifications observed among the Gobies, from which they differ only in having the ventral fins non-coalescent. On the whole they are somewhat larger than the Gobies, and rather freshwater than marine species, some of them being abundant in the rivulets of the islands of the Indo-Pacific and Atlantic. Others have even penetrated into the inland-waters of the African continent.

TRYPAUCHEN.--Body elongate, covered with minute scales;
head compressed, with a deep cavity on each side, above the
operculum. Teeth small, in a band. One dorsal, the spinous
portion composed of six spines; dorsal and anal fins continuous
with the caudal, ventral fins united.

Small fishes of singular aspect, from the East Indian coasts. Three species, of which _T. vagina_ is common.

CALLIONYMUS.--Head and anterior part of the body depressed,
the rest cylindrical, naked. Snout pointed, with the cleft
of the mouth narrow, horizontal, and with the upper jaw very
protractile. Eyes rather large, more or less directed upwards.
Teeth very small, palate smooth. A strong spine at the angle of
the præoperculum. Two dorsal fins, the anterior with three or
four flexible spines; ventrals five-rayed, widely apart from
each other. Gill-openings very narrow, generally reduced to a
foramen on the upper side of the operculum.

The “Dragonets” are small, and generally beautifully coloured marine fishes, inhabitants of the coasts of the temperate zone of the Old World; the minority of species live in tropical parts of the Indo-Pacific; and these seem to descend to somewhat greater depths than the littoral species of the northern hemisphere. Secondary sexual characters are developed in almost all the species, the mature males having the fin-rays prolonged into filaments, and the fin-membranes brightly ornamented. On the British coast one species (_C. draco_) is very common, and locally called “Skulpin.” About thirty species are known, many of which have the præopercular spine armed with processes or barbs. _Vulsus_ is allied to _Callionymus_.

Other genera belonging to this family are--_Benthophilus_ from the Caspian Sea; _Amblyopus_, _Orthostomus_, _Platyptera_, _Luciogobius_, _Oxymetopon_, and, perhaps, _Oxuderces_.

TENTH DIVISION--ACANTHOPTERYGII BLENNIIFORMES.

_Body low, sub-cylindrical or compressed, elongate. Dorsal fin very long; the spinous portion of the dorsal, if distinct, is very long, as well developed, as the soft, or much more; sometimes the entire fin is composed of spines only; anal more or less long; caudal fin subtruncated or rounded, if present. Ventral fins thoracic or jugular, if present._

FIRST FAMILY--CEPOLIDÆ.

_Body very elongate, compressed, covered with very small cycloid scales; eyes rather large, lateral. Teeth of moderate size. No bony stay for the angle of the præoperculum. One very long dorsal fin, which, like the anal, is composed of soft rays. Ventrals thoracic, composed of one spine and five rays. Gill-opening wide. Caudal vertebræ exceedingly numerous._

The “Band-fishes” (_Cepola_) are small marine fishes, belonging principally to the fauna of the northern temperate zone; in the Indian Ocean the genus extends southwards to Pinang. The European species (_C. rubescens_) is found in isolated examples on the British coast, but is less scarce in some years than in others. These fishes are of a nearly uniform red colour.

SECOND FAMILY--TRICHONOTIDÆ.

_Body elongate, sub-cylindrical, covered with cycloid scales of moderate size. Eyes directed upwards. Teeth in villiform bands. No bony stay for the angle of the præoperculum. One long dorsal fin, with simple articulated rays, and without a spinous portion; anal long. Ventrals jugular, with one spine and five rays. Gill-opening very wide. The number of caudal vertebræ much exceeding that of the abdominal._

Small marine fishes, belonging to two genera only, _Tricho__notus_ (_setigerus_) from Indian Seas, with some of the anterior dorsal rays prolonged into filaments; and _Hemerocoetes_ (_acanthorhynchus_) from New Zealand, and sometimes found far out at sea on the surface.

THIRD FAMILY--HETEROLEPIDOTIDÆ.

_Body oblong, compressed, scaly; eyes lateral; cleft of the mouth lateral; dentition feeble. The angle of the præoperculum connected by a bony stay with the infraorbital ring. Dorsal long, with the spinous and soft portions equally developed; anal elongate. Ventrals thoracic, with one spine and five rays._

Small shore-fishes, characteristic of the fauna of the Northern Pacific, some of the species occurring on the American as well as Asiatic side. They have been referred to several genera, as

CHIRUS, which is distinguished by the presence of several
lateral lines;

OPHIODON, with one lateral line only, cycloid scales, and
slightly armed præoperculum;

AGRAMMUS, with one lateral line only, ctenoid scales, and
unarmed præoperculum; and

ZANIOLEPIS, with one lateral line and minute comb-like scales.

FOURTH FAMILY--BLENNIIDÆ.

_Body elongate, low, more or less cylindrical, naked or covered with scales, which generally are small. One, two, or three dorsal fins occupying nearly the whole length of the back, the spinous portion, if distinct, being as much developed as the soft, or more; sometimes the entire fin is composed of spines; anal fin long. Ventrals jugular, composed of a few rays, and sometimes rudimentary or entirely absent. Pseudobranchiæ generally present._

Littoral forms of great generic variety, occurring abundantly in all temperate and tropical seas. Some of the species have become acclimatised in fresh water, and many inhabit brackish water. With very few exceptions they are very small, some of the smallest fishes belonging to the family of “Blennies.” One of the principal characteristics of the Blennies is the ventral fin, which is formed by less than five rays, and has a jugular position. The Blennies have this in common with many Gadoids, and it is sometimes difficult to decide to which of these two families a fish should be referred. In such doubtful cases the presence of the pseudobranchiæ (which are absent in Gadoids) may be of assistance.

In many Blennies the ventral fins have ceased to have any function, and become rudimentary, or are even entirely absent. In others the ventral fins, although reduced to cylindrical stylets, possess a distinct function, and are used as organs of locomotion, by the aid of which the fish moves rapidly over the bottom.

The fossil forms are scarcely known; _Pterygocephalus_ from Monte Bolca appears to have been a Blennioid.

ANARRHICHAS.--Body elongate, with rudimentary scales; snout
rather short; cleft of the mouth wide; strong conical teeth in
the jaws, those on the sides with several pointed tubercles; a
biserial band of large molar teeth on the palate. Dorsal fin
long, with flexible spines; caudal separate. Ventrals none.
Gill-openings wide.

The “Sea-wolf,” or “Sea-cat” (_A. lupus_), is a gigantic Blenny, attaining to a length of more than six feet. With its enormously strong tubercular teeth it is able to crush the hardest shells of Crustaceans or Mollusks, on which it feeds voraciously. It is an inhabitant of the northern seas, like two other allied species, all of which are esteemed as food by the inhabitants of Iceland and Greenland. Two other species of Sea-wolves occur in the corresponding latitudes of the North Pacific.

BLENNIUS.--Body moderately elongate, naked; snout short. A
single dorsal, without detached portion; ventrals jugular,
formed by a spine and two rays. Cleft of the mouth narrow; a
single series of immovable teeth in the jaws; generally a curved
tooth behind this series in both jaws, or in the lower only. A
more or less developed tentacle above the orbit. Gill-opening
wide.

About forty species of Blennius (in the restricted generic sense) are known from the northern temperate zone, the tropical Atlantic, Tasmania, and the Red Sea. But in the tropical Indian Ocean they are almost entirely absent, and replaced by other allied genera. Three species, found near the Sandwich Islands, are immigrants into the Pacific from the American Continent. They generally live on the coast, or attach themselves to floating objects, some species leading a pelagic life, hiding themselves in floating seaweed, in which they even propagate their species. All species readily accustom themselves to fresh water, and some (_B. vulgaris_) have become entirely acclimatised in inland lakes. British species are _B. gattorugine_ (growing to a length of twelve inches), _B. ocellaris_, _B. galerita_, and _B. pholis_, the common “Shanny.”

_Chasmodes_ is a genus allied to _Blennius_, from the Atlantic coasts of temperate North America.

PETROSCIRTES.--Body moderately elongate, naked. Snout generally
short. A single dorsal fin; ventrals composed of two or three
rays. Cleft of the mouth narrow; a single series of immovable
teeth in the jaws; a strong curved canine tooth behind this
series, that of the lower jaw much stronger than that of the
upper. Head sometimes with tentacles. Gill-opening reduced to a
small fissure above the root of the pectoral.

Thirty species, from the tropical Indo-Pacific, of small size.

SALARIAS.--Body moderately elongate, naked; snout short, with
transverse cleft of the mouth; a series of numerous small
teeth in the jaws, implanted in the gum and movable; generally
a curved canine tooth on each side of the lower jaw, behind
the series of small teeth. Dorsal fin continuous, sometimes
divided into two portions by a more or less deep notch without a
detached anterior part. Ventral fins with two or three rays. A
tentacle above the orbit. Gill-openings wide.

Sixty species are known from the tropical zone, extending northwards to Madeira, southwards to Chile and Tasmania. In certain individuals of some of the species a longitudinal cutaneous crest is developed; all young individuals lack it, and in some other species it is invariably absent. Singularly enough this crest is not always a sexual character, as one might have supposed from analogy, but in some species at least it is developed in both sexes. Mature males, however, have generally higher dorsal fins and a more intense and variegated coloration than females and immature males, as is also the case in _Blennius_.

CLINUS.--Body moderately elongate, covered with small scales;
snout rather short; a narrow band or series of small teeth in
the jaws and on the palate. Dorsal fin formed by numerous spines
and a few soft rays, without a detached anterior portion; anal
spines two. Ventrals with two or three rays. A tentacle above
the orbit. Gill-opening wide.

Thirty species, from the coasts of tropical America and the southern temperate zone. Three other genera are closely allied to Clinus, viz. _Cristiceps_ and _Cremnobates_, in which the three anterior dorsal spines are detached from the rest of the fin; and _Tripterygium_, with three distinct dorsal fins, of which the two anterior are spinous. The species of these genera are as numerous as those of _Clinus_, occurring in many parts of tropical seas, in the Mediterranean, and being especially well represented in South Australia and New Zealand.

STICHÆUS.--Body elongate, covered with very small scales;
lateral line more or less distinct, sometimes several lateral
lines. Snout short; very small teeth in the jaws, and generally
on the palate. Dorsal fin long, formed by spines only. Ventrals
with two or three rays. Caudal fin distinct. Gill-openings
rather wide.

Small fishes, peculiar to the coasts near the arctic circle, ranging southwards to the coasts of Japan and Scandinavia. Ten species.

BLENNIOPS.--Body moderately elongate, covered with very small
scales; lateral line none. Snout short; small teeth in the
jaws, none on the palate. Dorsal fin long, formed by spines
only. Ventrals with one spine and three rays. Caudal distinct.
Gill-openings of moderate width, the gill-membranes coalescent
across the isthmus.

A fine but not common kind of Blenny (_B. ascanii_), from the British and Scandinavian coasts.

CENTRONOTUS.--Body elongate, covered with very small scales;
lateral line none. Snout short; very small teeth in the jaws.
Dorsal fin long, formed by spines only. Ventrals none or
rudimentary; caudal separate. Gill-openings of moderate width,
gill-membranes coalescent.

Ten species are known from the northern coasts; southwards the genus extends to the coasts of France, New York, California, and Japan. _C. gunellus_, or the “Gunnel-fish” or “Butter-fish,” is common on the British coasts. _Apodichthys_ is allied to _Centronotus_, but the vertical fins are confluent; and a very large, excavated, pen-like spine lies hidden in a pouch in front of the anal fin. This spine is evidently connected in some way with the generative organs, as a furrow leads from the orifice of the oviduct to the groove of the spine. One species from the Pacific coast of North America. _Xiphidion_ is another closely allied genus from the same locality.

CRYPTACANTHODES.--Body very elongate, naked, with a single
lateral line. Head with the muciferous system well developed.
Eye rather small. Conical teeth in the jaws, on the vomer
and palatine bones. One dorsal formed by spines only; caudal
connected with dorsal and anal. Ventrals none. Gill-opening of
moderate width, with the gill-membranes joined to the isthmus.

One species (_C. maculatus_) from the Atlantic coasts of North America.

PATÆCUS.--Body oblong, elevated anteriorly; snout short, with
subvertical anterior profile; minute teeth in the jaws and on
the vomer. Dorsal fin with the anterior spines strong and long,
continuous with the caudal; ventrals none. Gill-openings wide.

Three species of this singular form are known from South and West Australia.

ZOARCES.--Body elongate, with the scales rudimentary; conical
teeth in the jaws. Dorsal fin long, with a depression on the
tail, which is formed by a series of spines much shorter than
the rays. No other fin-spines. No separate caudal fin. Ventrals
short, formed by three or four rays. Gill-openings wide.

Two species are known, one from the European, and the other from the North American side of the Atlantic. The former, _Z. viviparus_, is well known by the name of “Viviparous Blenny;” as is signified by this name it produces its young alive. These are so matured at the time of their birth that on their first exclusion they swim about with the utmost agility. No fewer than from two to three hundred young are sometimes produced by one female, and the abdomen of the mother is so distended before parturition that it is impossible to touch it without causing them to be extruded. Full grown individuals are about twelve inches long, but the American species (_Z. anguillaris_) attains to a length of two or three feet.

Other genera of the family of Blennoids are:--_Blennophis_, _Nemophis_, _Plagiotremus_, _Neoclinus_, _Cebidichthys_, _Myxodes_, _Heterostichus_, _Dictyosoma_, _Lepidoblennius_, _Dactyloscopus_, _Gunellichthys_, _Urocentrus_, _Stichæopsis_, _Sticharium_, _Notograptus_, _Pholidichthys_, and _Pseudoblennius_.

FIFTH FAMILY--ACANTHOCLINIDÆ.

_Body elongate, low, compressed, covered with small scales. One dorsal fin, occupying nearly the whole of the back, and chiefly composed of spines. Anal fin long, with numerous spines. Ventrals jugular, composed of a few rays only._

Of this family one fish only is known (_Acanthoclinus littoreus_), a small Blenny abundant on the coast of New Zealand.

SIXTH FAMILY--MASTACEMBELIDÆ.

_Body elongate, eel-like, covered with very small scales. Mandible long, but little moveable. Dorsal fin very long, the anterior portion composed of numerous short isolated spines; anal fin with spines anteriorly. Ventrals none. The humeral arch is not suspended from the skull. Gill-openings reduced to a slit at the lower part of the side of the head._

Freshwater-fishes characteristic of and almost confined to the Indian region. The structure of the mouth and of the branchial apparatus, the separation of the humeral arch from the skull, the absence of ventral fins, the anatomy of the abdominal organs, affords ample proof that these fishes are Acanthopterygian eels. Their upper jaw terminates in a pointed moveable appendage, which is concave and transversely striated inferiorly in _Rhynchobdella_, and without transverse striæ in _Mastacembelus_: the only two genera of this family. Thirteen species are known, of which _Rh. aculeata_, _M. pancalus_ and _M. armatus_ are extremely common, the latter attaining to a length of two feet. Outlying species are _M. aleppensis_ from Mesopotamia and Syria, and _M. cryptacanthus_, _M. marchei_, and _M. niger_, from West Africa.

ELEVENTH DIVISION--ACANTHOPTERYGII MUGILIFORMES.

_Two dorsal fins more or less remote from each other; the anterior either short, like the posterior, or composed of feeble spines. Ventral fins with one spine and five rays, abdominal._

FIRST FAMILY--SPHYRÆNIDÆ.

_Body elongate, sub-cylindrical, covered with small cycloid scales; lateral line continuous. Cleft of the mouth wide, armed with strong teeth. Eye lateral, of moderate size. Vertebræ twenty-four._

This family consists of one genus only, _Sphyræna_, generally called “Barracudas,” large voracious fishes from the tropical and sub-tropical seas, which prefer the vicinity of the coast to the open sea. They attain to a length of eight feet, and a weight of forty pounds; individuals of this large size are dangerous to bathers. They are generally used as food, but sometimes (especially in the West Indies) their flesh assumes poisonous qualities, from having fed on smaller poisonous fishes. Seventeen species.

The Barracudas existed in the tertiary epoch, their remains being frequently found at Monte Bolca. Some other fossil genera have been associated with them, but as they are known from jaws and teeth or vertebræ only, their position in the system cannot be exactly determined; thus _Sphyrænodus_ and _Hypsodon_ from the chalk of Lewes, and the London clay of Sheppey. The American _Portheus_ is allied to _Hypsodon_. Another remarkable genus from the chalk, _Saurocephalus_, has been also referred to this family.[44]

SECOND FAMILY--ATHERINIDÆ.

_Body more or less elongate, sub-cylindrical, covered with scales of moderate size; lateral line indistinct. Cleft of the mouth of moderate width, with the dentition feeble. Eye lateral, large or of moderate size. Gill-openings wide. Vertebræ very numerous._

Small carnivorous fishes inhabiting the seas of the temperate and tropical zones; many enter fresh water, and some have been entirely acclimatised in it. This family seems to have been represented in the Monte Bolca formation by _Mesogaster_.

ATHERINA.--Teeth very small; scales cycloid. The first dorsal is
short and entirely separated from the second. Snout obtuse, with
the cleft of the mouth straight, oblique, extending to or beyond
the anterior margin of the eye.

The Atherines are littoral fishes, living in large shoals, which habit has been retained by the species acclimatised in fresh water. They rarely exceed a length of six inches, but are nevertheless esteemed as food. From their general resemblance to the real Smelt they are often thus misnamed, but may always be readily recognised by their small first spinous dorsal fin. The young, for some time after they are hatched, cling together in dense masses, and in numbers almost incredible. The inhabitants of the Mediterranean coast of France call these newly hatched Atherines “Nonnat” (unborn). Some thirty species are known, of which _A. presbyter_ and _A. boyeri_ occur on the British coast.

ATHERINICHTHYS, distinguished from _Atherina_ in having the
snout more or less produced; and the cleft of the mouth
generally does not extend to the orbit.

These Atherines are especially abundant on the coasts and in the fresh waters of Australia and South America. Of the twenty species known, several attain a length of eighteen inches and a weight of more than a pound. All are highly esteemed as food; but the most celebrated is the “Pesce Rey” of Chile (_A. laticlavia_).

TETRAGONURUS.--Body rather elongate, covered with strongly
keeled and striated scales. The first dorsal fin is composed
of numerous feeble spines, and continued on to the second.
Lower jaw elevated, with convex dental margin, and armed with
compressed, triangular, rather small teeth, in a single series.

This very remarkable fish is more frequently met with in the Mediterranean than in the Atlantic, but generally scarce. Nothing is known of its habits; when young it is one of the fishes which accompany Medusæ, and, therefore, it must be regarded as a pelagic form. Probably, at a later period of its life, it descends to greater depths, coming to the surface at night only. It grows to a length of eighteen inches.

THIRD FAMILY--MUGILIDÆ.

_Body more or less oblong and compressed, covered with cycloid scales of moderate size; lateral line none. Cleft of the mouth narrow or of moderate width, without or with feeble teeth. Eye lateral, of moderate size. Gill-opening wide. The anterior dorsal fin composed of four stiff spines. Vertebræ twenty-four._

The “Grey Mullets” inhabit in numerous species and in great numbers the coasts of the temperate and tropical zones. They frequent brackish waters, in which they find an abundance of food which consists chiefly of the organic substances mixed with mud or sand; in order to prevent larger bodies from passing into the stomach, or substances from passing through the gill-openings, these fishes have the organs of the pharynx modified into a filtering apparatus. They take in a quantity of sand or mud, and, after having worked it for some time between the pharyngeal bones, they eject the roughest and indigestible portion of it. The upper pharyngeals have a rather irregular form; they are slightly arched, the convexity being directed towards the pharyngeal cavity, tapering anteriorly and broad posteriorly. They are coated with a thick soft membrane, which reaches far beyond the margin of the bone, at least on its interior posterior portion; this membrane is studded all over with minute horny cilia. The pharyngeal bone rests upon a large fatty mass, giving it a considerable degree of elasticity. There is a very large venous sinus between the anterior portion of the pharyngeal and the basal portion of the branchial arches. Another mass of fat, of elliptical form, occupies the middle of the roof of the pharynx, between the two pharyngeal bones. Each branchial arch is provided on each side, in its whole length, with a series of closely-set gill-rakers, which are laterally bent downwards, each series closely fitting into the series of the adjoining arch; they constitute together a sieve, admirably adapted to permit a transit for the water, retaining at the same time every other substance in the cavity of the pharynx.

The lower pharyngeal bones are elongate, crescent-shaped, and broader posteriorly than anteriorly. Their inner surface is concave, corresponding to the convexity of the upper pharyngeals, and provided with a single series of lamellæ, similar to those of the branchial arches, but reaching across the bone from one margin to the other.

The intestinal tract shows no less peculiarities. The lower portion of the œsophagus is provided with numerous long thread-like papillæ, and continued into the oblong-ovoid membranaceous cœcal portion of the stomach, the mucosa of which forms several longitudinal folds. The second portion of the stomach reminds one of the stomach of birds; it communicates laterally with the other portion, is globular, and surrounded by an exceedingly strong muscle. This muscle is not divided into two as in birds, but of great thickness in the whole circumference of the stomach, all the muscular fasciculi being circularly arranged. The internal cavity of this stomach is rather small, and coated with a tough epithelium, longitudinal folds running from the entrance opening to the pyloric, which is situated opposite to the other. A low circular valve forms a pylorus. There are five rather short pyloric appendages. The intestines make a great number of circumvolutions, and are seven feet long in a specimen thirteen inches in length.

Some seventy species of Grey Mullets are known, the majority of which attain to a weight of about four pounds, but there are many which grow to ten and twelve pounds. All are eaten, and some even esteemed, especially when taken out of fresh water. If attention were paid to their cultivation, great profits could be made by fry being transferred into suitable backwaters on the shore, in which they rapidly grow to a marketable size. Several species are more or less abundant on the British coasts, as _Mugil octo-radiatus_ (Fig. 105, p. 254), _M. capito_, _M. auratus_ (Fig. 106, p. 254), and _M. septentrionalis_ (Fig. 107, p. 254), which, with the aid of the accompanying figures, and by counting the rays of the anal fin, may be readily distinguished--_M. octo-radiatus_ having eight, and _M. capito_ and _M. auratus_ nine soft rays. A species inhabiting fresh waters of Central America (_M. proboscideus_) has the snout pointed and fleshy, thus approaching certain other freshwater and littoral Mullets, which, on account of a modification of the structure of the mouth, have been formed into a distinct genus, _Agonostoma_. _Myxus_ comprises Mullets with teeth more distinct than in the typical species.

This genus existed in the tertiary epoch, remains of a species having been found in the gypsum of Aix, in Provence.

TWELFTH DIVISION--ACANTHOPTERYGII GASTROSTEIFORMES.

_The spinous dorsal is composed of isolated spines if present; the ventrals are either thoracic or have an abdominal position in consequence of the prolongation of the pubic bones which are attached to the humeral arch. Mouth small, at the end of the snout which is generally more or less produced._

FIRST FAMILY--GASTROSTEIDÆ.

_Body elongate, compressed. Cleft of the mouth oblique; villiform teeth in the jaws. Opercular bones not armed; infraorbitals covering the cheek; parts of the skeleton forming incomplete external mails. Scales none, but generally large scutes along the side. Isolated spines in front of the soft dorsal fin. Ventral fins abdominal, joined to the pubic bone, composed of a spine and a small ray. Branchiostegals three._

Of “Sticklebacks” (_Gastrosteus_) about ten species are satisfactorily known, one of which (_G. spinachia_) lives in salt and brackish water, whilst the others inhabit principally fresh waters, although they all are able to exist in the sea. They are confined to the Temperate and Arctic zones of the northern hemisphere. The British freshwater species are the Three-spined Stickleback (_G. aculeatus_), which sometimes, especially in Central Europe, lacks scutes, sometimes has a series of scutes along the side of the body; the Four-spined Stickleback (_G. spinulosus_) and the Nine-spined Stickleback (_G. pungitius_). The commonest North American species is _G. noveboracensis_. The habits of all the freshwater species are very similar. The common European species (_G. aculeatus_) is an active and greedy little fish, extremely destructive to the fry of other species, and consequently injurious in ponds where these are sought to be preserved. It is scarcely to be conceived what damage these little fishes do, and how greatly detrimental they are to the increase of all the fishes in general among which they live; for it is with the utmost industry, sagacity, and greediness that they seek out and destroy all the young fry that come their way. A small Stickleback, kept in an aquarium, devoured, in five hours’ time, seventy-four young dace, which were about a quarter of an inch long, and of the thickness of a horse hair. Two days after it swallowed sixty-two; and would, probably, have eaten as many every day could they have been procured. The Stickleback sometimes swarms in prodigious numbers. Pennant states that at Spalding, in Lincolnshire, there was once in seven years amazing shoals, which appear in the Welland, coming up the river in the form of a vast column. The quantity may, perhaps, be conceived from the fact that a man employed in collecting them, gained, for a considerable time, four shillings a-day by selling them at the rate of a halfpenny a bushel. Costa, who studied the manners of these small fishes, relates that, on the approach of spawning time, the male builds a nest of stalks of grass and other matters in a hollow of the bottom, a little above three inches wide and about six inches and a half deep, creeping over the materials on his belly, and cementing them with the mucus that exudes from his skin. The bottom of the nest is first laid, then the sides are raised, and lastly the top is covered over. A small hole is left on one side for an entrance. When the erection is complete, he seeks out a female, and conducting her, Costa says, with many caresses, to the nest, introduces her by the door into the chamber. In a few minutes she has laid two or three eggs, after which she bores a hole on the opposite side of the nest to that by which she entered, and makes her escape. The nest has now two doors, and the eggs are exposed to the cool stream of water, which, entering by one door flows out at the other. Next day the male goes again in quest of a female, and sometimes brings back the same, sometimes finds a new mate. This is repeated until the nest contains a considerable number of eggs, and each time the male rubs his side against the female and passes over the eggs. Next the male watches a whole month over his treasure, defending it stoutly against all invaders, and especially against his wives, who have a great desire to get at the eggs. When the young are hatched and able to do for themselves his cares cease.

The Sea-Stickleback (_G. spinachia_) is likewise a nest builder, choosing for its operations especially the shallows of brackish water, which are covered with _Zostera_.

SECOND FAMILY--FISTULARIIDÆ.

_Fishes of greatly elongated form; the anterior bones of the skull are much produced, and form a long tube, terminating in a narrow mouth. Teeth small; scales none, or small. The spinous dorsal fin is either formed by feeble isolated spines or entirely absent; the soft dorsal and anal of moderate length, ventral fins thoracic or abdominal, composed of five or six rays, without spine; if abdominal, they are separate from the pubic bones, which remain attached to the humeral arch. Branchiostegals five._

The “Flute-mouths” are also frequently called “Pipe-fishes,” a name which they have in common with the Syngnathidæ. They are gigantic marine Sticklebacks, living near the shore, from which they are frequently driven into the open sea; some of the species, therefore, have a wide geographical range. Probably all enter brackish water. They are distributed over the whole of the tropical and sub-tropical parts of the Atlantic and Indo-Pacific. The species are few in number, but some of them are very common.

This family is well represented in Eocene formations; some of the remains belonging to the existing genera, _Fistularia_, _Aulostoma_, and _Auliscops_, the two former of which occur not rarely at Monte Bolca and in the schists of Glaris. Well-preserved remains of _Auliscops_ have been found in the Marl-slates of the highlands of Padang in Sumatra. Extinct genera from Monte Bolca are _Urosphen_, the cylindrical body of which is terminated by a large cuneiform fin; and _Rhamphosus_, which has an immense spinous ray, denticulated behind, inserted on the nape.

FISTULARIA.--Body scaleless; caudal fin forked, with the two
middle rays produced into a filament; no free dorsal spines.

Three species are known, common on the shores of the Tropical Atlantic (_F. tabaccaria_) and Indian Oceans (_F. serrata_ and _F. depressa_); they attain to a length of from four to six feet.

The anterior portion of the vertebral column shows the same peculiarity as in _Dactylopterus_; it is a long compressed tube, composed of four elongate vertebræ, which are perfectly anchylosed; each of them has a pair of small foramina for blood-vessels. The neural spines and parapophyses of this tubiform portion are confluent into thin laminæ, the lateral of which are wing-like, and expanded in their anterior half.

AULOSTOMA.--Body covered with small scales. Caudal fin rhombic,
without prolonged rays; a series of isolated feeble dorsal
spines. Teeth rudimentary.

Two species from the Tropical Atlantic and Indian Oceans.

AULISCOPS.--Body naked. Ventrals thoracic. Numerous spines in
front of the dorsal fin.

One species (_A. spinescens_) from the Pacific coast of North America. _Aulorhynchus_ from the same sea, and _Aulichthys_ from Japan, are allied genera.

THIRTEENTH DIVISION--ACANTHOPTERYGII CENTRISCIFORMES.

_Two dorsal fins; the spinous short, the soft and the anal of moderate extent. Ventral fins truly abdominal, imperfectly developed._

This division consists of one family, _Centriscidæ_, with two genera. The fishes belonging to it are very small, marine, and, in consequence of their limited power of swimming, often driven out into the open sea. They have the same structure of the mouth and snout as the Fistulariidæ, but combine with it peculiarities of the shape of body, of the structure of the vertical fins, and of the relations between endo- and exo-skeleton, which render them altogether a singular and interesting type. _Amphisile_ has been found in a fossil state at Monte Bolca.

CENTRISCUS.--Body oblong or elevated, compressed, covered with
small rough scales; lateral line none; some bony strips on the
side of the back, and on the margin of the thorax and abdomen;
the former, in one species, are confluent and form a shield.
Teeth none. Two dorsal fins, the first with one of the spines
very strong. Ventral fins small, abdominal, composed of five
soft rays. Four branchiostegals.

Of the four species the most generally known is _C. scolopax_, the “Trumpet-fish” or “Bellows-fish,” which rarely occurs on the south coast of England, is more common farther south, and reappears in Tasmania. The allied _C. gracilis_ is one of the fishes common to the Mediterranean and Japanese Seas. The species figured, _C. humerosus_, occurs on the coast of South Australia, and is very scarce.

AMPHISILE.--Body elongate, strongly compressed, provided with a
dorsal cuirass, which is formed by portions of the skeleton; the
longitudinal axis of the tail is not in the same line with that
of the trunk. Scales none. Teeth none. Two dorsal fins situated
on the hindmost part of the back; ventral fins rudimentary,
abdominal. Three or four branchiostegals.

The three species known of this genus are found in the tropical Indo-Pacific. Their body is so thin that it has the appearance of being artificially compressed between two sheets of paper; it is semi-transparent, especially in the region of the air-bladder. The structure of the vertebral column is extremely singular and unique among Acanthopterygians. The abdominal portion is more than four times as long as the caudal; nevertheless it is composed of only six vertebræ, whilst the latter consists of fourteen. The abdominal vertebræ are extremely slender, the third alone being nearly as long as the whole caudal portion; they have a slight ridge superiorly and inferiorly, and on each side; the whole portion lying in the uppermost concavity of the dorsal cuirass. The caudal vertebræ are extremely short, and the strength of their neural and hæmal spines is in proportion to their size. The dorsal cuirass is not a dermal production, but formed by modified parts of the endoskeleton; its composition, the number and condition of its single parts, and, finally, the first dorsal spine, which in _A. punctulata_ is so singularly attached to it, favour this opinion. The plates, which occupy the vertebral line, would correspond to the neural spines, and the lateral plates on which the ribs are suspended to the parapophyses. _Amphisile_ may be considered as a Chelonian form among fishes.

FOURTEENTH DIVISION--ACANTHOPTERYGII GOBIESOCIFORMES.

_No spinous dorsal; the soft and the anal short or of moderate length, situated on the tail; ventral fins subjugular, with an adhesive apparatus between them. Body naked._

These fishes are well characterised by their single dorsal fin, and by their adhesive ventral apparatus, which has only an external similarity to the organ observed in _Cyclopterus_ and _Liparis_; its structure is typically different from it. Whilst in those genera the ventral fins occupy the centre of the disk forming its base, these fins are here widely apart from each other, as in _Callionymus_, forming only a portion of the periphery of the disk, which is completed by a cartilaginous expansion of the coracoid bones. The following description of its structure is taken from _Sicyases sanguineus_, but it is essentially the same in all the genera.

The whole disk is exceedingly large, subcircular, longer than broad, its length being one-third of the whole length of the fish. The central portion is formed merely by skin, which is separated from the pelvic or pubic bones by several layers of muscles. The peripheric portion is divided into an anterior and posterior part by a deep notch behind the ventrals. The anterior peripheric portion is formed by the four ventral rays, the membrane between them, and a broad fringe which extends anteriorly from one ventral to the other; this fringe is a fold of the skin, containing on each side the rudimentary ventral spine, but no cartilage. The posterior peripheric portion is suspended on each side from the coracoid, the upper bone of which is exceedingly broad, becoming a free movable plate behind the pectoral. A broad cartilage is firmly attached to it. The lower bone of the coracoid is of a triangular form, and supports a very broad fold of the skin, extending from one side to the other, and containing a cartilage which runs through the whole of that fold. Five processes of the cartilage are continued into the soft striated margin in which the disk terminates posteriorly. The surface of the disk is coated with thick epidermis, like the sole of the foot of higher animals. The epidermis is divided into many polygonal plates; there are no such plates between the roots of the ventral fins.

Not less unique is the structure of the bones which have some relation to this external adhesive apparatus. As exemplified by _Chorismochismus dentex_ the coracoid is well developed, and, as usual, composed of two pieces, the upper of which is not suspended from the humerus, but fixed by a ligament to the hinder margin of the carpal bones. It is a broad lamella, dilated posteriorly into the cartilage, which is externally visible; the lower piece is narrower, and fixed to the extremity of the pubic bone of its side. The pubic bones are united by suture, and form together a heart-shaped disk, the point of which is produced backwards. The anterior portion of the disk is concave, with a bony longitudinal bridge and a feeble transverse ridge. The disk is fixed to the humeral bones by the convex portions of its anterior margin, whilst the convex portions of the lateral margins serve as base for the ventral fins. The latter are composed of one spine, which is transformed into a broad, thin, and curved plate, hidden below the skin, and apparently of four rays; but on closer examination we find that the hidden ray has a longitudinal groove anteriorly, in which another thinner ray lies concealed. This ray is quite free, and not joined to the pubic bone.

The fishes belonging to the single family of this division, _Gobiesocidæ_, are strictly marine but littoral fishes. They are scattered over the temperate zones of both hemispheres, and more numerous than between the Tropics. All are of small or very small size.

The adhesive disk consists of an anterior and posterior division. In some of the genera the posterior division has no free anterior margin, the teeth being either all conical, as in _Chorisochismus_ (Cape of Good Hope) and _Cotylis_ (Red Sea and Indian Ocean); or incisor-like in both jaws, as in _Sicyases_ (coast of Chili and West Indies); or incisor-like at least in the lower jaw, as in _Gobiesox_ (West Indies and Pacific coasts of South America). In other genera the posterior portion of the adhesive disk has a free anterior margin. Only one of these genera has incisor-like teeth, viz. _Diplocrepis_ from New Zealand. In the remaining genera, _Crepidogaster_ (from Tasmania and South Australia), _Trachelochismus_ (from New Zealand and the Fiji Islands), _Lepadogaster_, and _Leptopterygius_, the teeth are very small and fine. The two last genera are European, and _Lepadogaster_ at least is common on the Southern British coasts. The three species known as British--_L. gouanii_, _L. candollii_, and _L. bimaculatus_--are prettily coloured, but subject to great variation.

FIFTEENTH DIVISION--ACANTHOPTERYGII CHANNIFORMES.

_Body elongate, covered with scales of moderate size; no spine in any of the fins; dorsal and anal long. No superbranchial organ, only a bony prominence on the anterior surface of the hyomandibular._