Chapter XXV: Appendix: To the Fishes: Palaeospondylidae—ostracodermi—heterostraci (6)

_Gobius_, of which several species are of common occurrence on our shores, have attracted special interest from their habits during the much prolonged breeding season. The male, usually more brilliantly coloured than the female, mounts guard over the eggs, which are either simply fixed by the female to the under surface of stones or weeds, or in a sort of nest built and kept in constant repair by him. This nest is usually made of a shell of _Cardium_, _Patella_, _Haliotis_, etc., or of the carapace of a crab, with the convexity turned upwards and covered with sand; the sand underneath is hollowed out, and a round opening at the side, coated by a mucus secreted by the skin of the male fish, gives access to the interior; the eggs, which are elongate and pyriform, are stuck to the inner surface of the shell forming the roof.[730] A curious British form is _Aphia pellucida_, two inches long which, from its transparent and almost colourless body, has long been erroneously supposed to be the fry of some larger fish. Among exotic forms, mention should be made of the Blind Goby (_Typhlogobius californiensis_), two inches long, uniform light pink, scaleless, with the eyes very small, reduced to mere vestiges, covered by skin, and functional only in the young, living like a slug under rocks between tide marks on the coast of California;[731] and to the Walking-Fish or Jumping-Fish (_Periophthalmus_), of which various species are found in great abundance on the mud-flats at the mouths of rivers in tropical Africa, Asia, and North-West Australia, skipping about by means of the muscular, scaly base of their pectoral fins, with the head raised and bearing a pair of strongly projecting versatile eyes close together.[732]

{691}DIVISION VI.—DISCOCEPHALI.

Highly aberrant Acanthopterygians with the anterior dorsal fin modified into a suctorial, transversely laminated oval disk[733] on the head, the skull being very much flattened and with simple basis cranii. The pectoral rays are inserted on the small, perforate, scapula and on four hour-glass-shaped pterygials, three of which are in contact with the coracoid. Ventrals thoracic.

FAM. 1. ECHENEIDIDAE.—Maxillary slender, adnate to the upper surface of the praemaxillary; suborbital arch slender. Pectoral fin inserted high up; supraclavicle much reduced; ventral fin with one spine and five soft rays. Body elongate and covered with small scales; soft dorsal and anal fins elongate and opposed to each other. All the praecaudal vertebrae with very strong parapophyses, the anterior with diapophyses as well; ribs and epipleurals nearly equally developed, both inserted at the extremity of the parapophyses.

In spite of a superficial external resemblance to the genus _Elacate_, the Sucking-Fish bear certainly no affinity to that genus nor to other Scombriformes, as first observed by Gill. They are probably derived from Perciformes, but from which family it is impossible to suggest. Three genera may be distinguished: _Opisthomyzon_, from the Upper Eocene of Switzerland, with a very small suctorial disk and 23 or 24 vertebrae; _Echeneis_, with large disk and 30 vertebrae; and _Remora_, distinguished from the second by a shorter body with only 27 vertebrae. These remarkable fishes, of which about 10 species are distinguished, are distributed all over the tropical and warm seas, and exceptionally carried as far north as the south coast of England. They feed on other fishes, and attach themselves by means of their cephalic {692}sucker to boats or to sharks, turtles, cetaceans, and other large swift-swimming animals. On the East Coast of Africa they are employed by the natives for catching turtles, to the carapace of which they stick with extraordinary tenacity, being held by a line attached to a metal ring round the caudal peduncle.[734] The largest Sucking-fish grows to a length of three feet.

DIVISION VII.—SCLEROPAREI.

Second suborbital bone more or less produced towards or ankylosed with the praeoperculum ("suborbital stay").[735] Ventral fins thoracic.

The "Cheek-armoured Acanthopterygians," "Joues cuirassées" of Cuvier, after the exclusion of the Sticklebacks, form a perfectly natural association, evidently derived from the Serranidae, with which the more generalised forms have much in common. From the Perch-like genus, _Sebastes_, a continuous series can be traced towards the Triglidae, especially through such forms as _Apistus_, _Minous_, and _Choridactylus_, in which one or more of the lower pectoral rays are detached from the rest of the fin. Through the Comephoridae the Scorpaenidae are connected with the Cottidae, whilst the latter merge insensibly into the still more aberrant Cyclopteridae. These conclusions, which are apparent enough from a mere comparison of the external characters, become fortified by a study of the skeletons. The passage between the various groups here accepted as families is so complete that no {693}serious objection could be raised to their union in one great family with a number of minor divisions.

The character from which the Scleroparei derive their name is subject to many modifications. The second suborbital (the third if the praeorbital be regarded as the first) may be merely enlarged and prolonged over the cheek towards the praeoperculum (_Sebastes_, _Anoplopoma_), or firmly ankylosed to the latter (_Scorpaena_, _Platycephalus_), or form part of the external armature of the head (_Trigla_, _Dactylopterus_). The structure of the base of the pectoral fin appears to afford important characters for the definition of the families, as first pointed out by Gill; these {694}characters have, however, not yet been tested on a sufficient number of the very numerous forms grouped under Cottidae, some of which I have already transferred to the Comephoridae.

SYNOPSIS OF THE FAMILIES.

I. Head not completely cuirassed.

A. Ventral fins not widely separated; none of the pectoral pterygials
in contact with the clavicle.

Two nostrils on each side; basis cranii double; gill-membranes free
from isthmus 1. _Scorpaenidae_.

A single nostril on each side; basis cranii double; gill-membranes
free from isthmus 2. _Hexagrammidae_.

Two nostrils on each side; basis cranii simple; gill-membranes free
or narrowly attached to isthmus 3. _Comephoridae_.

Two nostrils on each side; basis cranii simple; gill-opening
narrow, above base of pectoral 4. _Rhamphocottidae_.

B. Ventral fins, if present, not widely separated; one or several of
the pterygials in contact with the clavicle.

Ventral fins distinct; gill-clefts wide 5. _Cottidae_.

Ventral fins united into a sucking disk; gill-opening narrow, above
base of pectoral 6. _Cyclopteridae_.

C. Ventral fins widely separated; none of the pterygials in contact
with the clavicle.

Ventral fins behind base of pectorals; praecaudal vertebrae without
transverse processes 7. _Platycephalidae_.

Ventral fins a little in front of base of pectorals; praecaudal
vertebrae with transverse processes 8. _Hoplichthyidae_.

II. Head completely cuirassed.

Ventral fins narrowly separated; no pectoral appendages; pterygials
short and broad 9. _Agonidae_.

Ventral fins widely separated; 2 or 3 lowermost rays of pectoral
fin detached as feelers; pterygials short and broad
10. _Triglidae_.

Ventral fins narrowly separated; pectoral fin divided into two
portions; pterygials elongate 11. _Dactylopteridae_.

FAM. 1. SCORPAENIDAE.—Head not or but incompletely cuirassed, usually with spines; basis cranii double; parietal bones often meeting on the median line, over the supraoccipital; two nostrils on each side. Gill-membranes free from isthmus; gills 3½ or 4; pseudobranchiae present. Vertebrae 24 to 37, the anterior praecaudals with sessile ribs bearing epipleurals, the posterior with transverse processes, often directed downwards, or forming haemal arches, bearing the rib and the epipleural. Post-temporal more or less distinctly forked, more or less firmly ankylosed to the skull; scapula and coracoid well developed, in contact with each other or separated by cartilage; pectoral rays inserted {695}on the scapula and on 3 or 4 large, hour-glass or anvil-shaped pterygials, two of which are in contact with the coracoid. Ventral fins close together, with 1 spine and 3 to 5 soft rays. Spinous dorsal strong, usually longer than the soft, sometimes extending on the head; anal usually with 3 spines. Body covered with scales or naked.

A large family of carnivorous marine fishes, some descending to great depths, of nearly world-wide distribution, represented by three extinct genera (_Ampheristus_, _Histiocephalus_, _Scorpaenoides_) in the Eocene and by several species of _Scorpaena_ in later formations. About 250 recent species are known. Principal genera: _Sebastes_, _Setarches_, _Scorpaena_, _Pterois_, _Apistus_, _Minous_, _Pelor_, _Choridactylus_, _Centropogon_, _Gymnapistus_, _Amblyapistus_, _Pentaroge_, _Tetraroge_, _Gnathacanthus_ (_Holoxenus_), _Agriopus_, _Synancia_, _Polycaulus_.

Great variety of form obtains in this family, from the Perch-like _Sebastes_ to the extraordinary-shaped _Tetraroge_, _Pelor_, and _Synancia_. Many of its members are excellent examples of mimetic adaptation to the surrounding, resembling the rocks among which they live and being covered with dermal appendages simulating weeds. An interesting example of commensalism has been discovered by A. Alcock[736] in _Minous inermis_, off the coasts of India, which, wherever found, is always more or less incrusted with the {696}Gymnoblastic Hydroid _Stylactis minoi_. Many of the _Sebastes_ and their allies are of large size and used as food; some are viviparous, the young being produced in great numbers and very small in size. _Scorpaena_, _Pterois_, _Pelor_, and _Synancia_ are dangerous for the stings from their dorsal spines, which are provided with poison glands.[737]

FAM. 2. HEXAGRAMMIDAE.—Head not cuirassed, without strong spines; basis cranii double; a single nostril on each side. Gill-membranes free from isthmus; gills 4; pseudobranchiae present. Vertebrae 42 to 57, most of the praecaudals with transverse processes bearing the ribs and the epipleurals. Post-temporal forked; scapula and coracoid well developed, in contact with each other; pectoral rays inserted on the scapula and 4 anvil-shaped pterygials, 2 of which are in contact with the coracoid. Ventral fins close together, more or less behind the pectorals, with 1 spine and 5 soft rays. Spinous dorsal of usually rather feeble rays, nearly as long as or longer than the soft; anal elongate, with or without spines. Body covered with small scales.

Carnivorous fishes, mostly of large size, from the rocky coasts of the North Pacific. Some are highly valued as food. Twelve species, referable to 6 genera: _Hexagrammus_, _Pleurogrammus_, _Agrammus_, _Ophiodon_, _Zaniolepis_, _Oxylebius_. _Hexagrammus_ and _Pleurogrammus_ are remarkable in having 4 or 5 lateral lines on each side.

FAM. 3. COMEPHORIDAE.—Head not cuirassed, without spines; basis cranii simple; two nostrils on each side. Gill-membranes free or narrowly attached to isthmus; gills 4; pseudobranchiae present or absent. Vertebrae 42 to 64, some or most of the praecaudals with transverse processes bearing the ribs and the epipleurals. Post-temporal forked; scapula and coracoid well developed, in contact with each other or separated by cartilage; pectoral rays inserted on the scapula and on 4 anvil-shaped or plate-like pterygials, 2 of which are in contact with the coracoid. Ventral fins, if present, close together, with 1 spine and 3 to 5 soft rays. Spinous dorsal of rather feeble rays, as long as or shorter than the soft; anal spines feeble or absent. Body covered with small scales or naked.

{697}Four genera, each with a single species: _Anoplopoma_ (_Scombrocottus_), from the North Pacific from Unalaska to California; _Triglopsis_, from deep water in Lakes Michigan and Ontario; _Cottocomephorus_, from Lake Baikal, and _Comephorus_ from the greatest depths of that lake. As in many bathybial forms, _Comephorus_ is colourless and provided with very large eyes; ventral fins are absent and the skeleton is very thin and papery. As a result of this condition, the second suborbital is not produced over the cheek, a unique exception to the main characteristic of this division; but no doubt can be entertained as to the propriety of referring it to the neighbourhood of _Anoplopoma_, since the recently discovered _Cottocomephorus_ may be regarded as a connecting link between the two genera. _Comephorus_ is viviparous, and dies after parturition.[738] Jordan regards _Triglopsis_ as a relic of a former Arctic marine fauna.

FAM. 4. RHAMPHOCOTTIDAE.—Head incompletely cuirassed, with spines; basis cranii simple; two nostrils on each side. Gill-opening narrow, above the base of the pectoral; gills 3½. Vertebrae 24. Post-temporal short and flat, ankylosed to the skull; scapula and coracoid well developed, separated by cartilage; pectoral rays inserted on the scapula and on 4 plate-like pterygials, 2 of which are in contact with the coracoid. Ventral fins close together, behind the pectorals, with a rudimentary spine and 3 soft rays. Spinous dorsal shorter than the soft; no anal spines. Body densely covered with small prickly scales.

_Rhamphocottus richardsonii_, a small fish 3 inches in length, from the north-west coast of North America, is the only representative of this family.

FAM. 5. COTTIDAE.—Head not or but incompletely cuirassed, usually with spines; basis cranii simple; parietal bones often meeting on the median line; two nostrils on each side. Gill-membranes free or attached to isthmus; gills 3½ or 4; pseudobranchiae usually present. Vertebrae 24 to 50, the anterior praecaudals with sessile ribs, the posterior with transverse processes, often directed downwards, or forming haemal arches, bearing ribs and epipleurals. Post-temporal more or less distinctly forked; scapula and coracoid separated from each other {698}by the intervention of the plate-like pterygials, of which one, two, or three are in contact with the clavicle; the coracoid more or less reduced. Ventral fins close together, with 1 spine and 2 to 5 soft rays (absent in _Ereunias_). Spinous dorsal usually shorter than the soft, sometimes quite indistinct; anal without spines. Body naked, partially scaly, or with prickles or bony plates.

Mostly small carnivorous fishes, the largest (_Scorpaenichthys_) growing to about 3 feet. Some species inhabit fresh waters, but the majority are marine, a few descending to great depths. Nearly all are from the northern regions, but a genus allied to _Cottus_ (_Sclerocottus_) is from South Georgia, in the Antarctic region. Fossil Cottidae are known from the Upper Eocene and Miocene (_Eocottus_, _Lepidocottus_), and are distinguished from the modern forms in the smaller number of vertebrae (24 or 26 instead of 30 to 50). At least 220 species are known. Principal genera: _Jordania_, _Scorpaenichthys_, _Icelus_, _Triglops_, _Cottus_, _Cottunculus_, _Blepsias_, _Pseudoblennius_, _Hemitripterus_, _Synchirus_, _Ascelichthys_, _Psychrolutes_, _Ereunias_. The little freshwater "Miller's Thumb" (_Cottus gobio_) and the larger marine "Bull-heads" (_C. bubalis_ and _C. scorpius_) are the most familiar British representatives of this family. The eggs are deposited on stones, weeds, or other submerged objects, or in a sort of nest, and are guarded by the male, which in most species is distinguished by a large genital papilla; this, in some forms, acts as an intromittent organ.

FAM. 6. CYCLOPTERIDAE.—Very closely related to the preceding, with which they are connected through _Psychrolutes_, and it is even doubtful whether they deserve to be separated from them. The only important distinctive characters reside in the structure of the ventrals, which, if present (absent in _Paraliparis_, a close ally of _Liparis_), are united to form a sucking disk, and the small size of the gill-cleft. The body is short, tumid, tadpole-like, naked or tubercular; the spinous dorsal, if present, is short. Vertebrae 28 to 60, the skeleton feebly ossified.[739]

Sluggish fishes, feeding on small animals and plants, from the North Atlantic and Pacific Oceans, and the Arctic and Antarctic seas, many descending to great depths (1800 fathoms). About fifty species are distinguished. Principal genera: _Cyclopterus_, _Cyclopterichthys_, _Liparops_, _Liparis_, _Careproctus_, _Paraliparis_.

{699}The common Lump-Sucker of our coasts (_Cyclopterus lumpus_) is the largest member of the group, growing to a length of 2 feet or more. The male makes pits in the sand between stones, in which the female deposits the eggs; he watches over the eggs and also over the young, which cling to his body with their suckers. The "Sea-Snails" (_Liparis_), are represented by two species on the British coasts.

FAM. 7. PLATYCEPHALIDAE.—Head not cuirassed, much depressed, with spines; basis cranii simple; two nostrils on each side. Gill-membranes free; gills 4; pseudobranchiae present. Vertebrae 27; ribs all sessile, bearing the epipleurals. Post-temporal forked; scapula and coracoid well developed, in contact with each other; pectoral rays inserted on the scapula and on 4 short and broad pterygials, 2 of which are in contact with the coracoid. Ventral fins widely separated, behind the pectorals, with 1 spine and 5 soft rays. Spinous dorsal shorter than the soft; anal without spines. Body covered with small scales.

The single genus _Platycephalus_, with some 40 species, inhabits the coasts of the Indian Ocean and the Western Pacific.

FAM. 8. HOPLICHTHYIDAE.—Head incompletely cuirassed, much depressed, with spines; basis cranii simple; two nostrils on each side. Gill-membranes attached to isthmus; gills 4; pseudobranchiae present. Vertebrae about 30, the praecaudals with transverse processes. Post-temporal fused with the skull; scapula and coracoid in contact with each other; pectoral rays inserted on the scapula and on 3 plate-like pterygials. Ventral fins widely separated, a little before the pectorals, with 1 spine and 5 soft {700}rays. Spinous dorsal shorter than the soft; anal without spines. Back and sides with bony, prickly plates.

_Hoplichthys_, with a single species from the coasts of Japan and China. _Bembras_, with two species from the coasts of Japan, appears to be related to it, but the skeleton is still unknown; it differs in having the body covered with small scales and the gill-membranes free.

FAM. 9. AGONIDAE.—Head completely cuirassed, usually with spines; basis cranii simple; two nostrils on each side. Gill-membranes free or attached to isthmus; gills 3½; pseudobranchiae present. Vertebrae 35 to 50; ribs sessile. Post-temporal fused with the skull; scapula and coracoid in contact with each other, or separated by a cartilaginous space; pectoral rays inserted on the scapula and 3 or 4 plate-like pterygials. Ventral fins close together, with 1 spine and 2 soft rays. Spinous dorsal shorter than the soft, or absent; anal without spines. Body covered with bony plates.

Small fishes, mostly from the coasts of the Northern Atlantic and Pacific, extending into the Arctic Ocean; one species from the coast of Chili. _Bathyagonus_ occurs in the North Atlantic between 350 and 477 fathoms.

About 40 species are known. Principal genera: _Agonus_, _Agonopsis_, _Bathyagonus_, _Aspidophoroides_. The "Pogge," or Armed Bullhead (_Agonus cataphractus_), is the only British species of this family.

FAM. 10. TRIGLIDAE.—Head completely cuirassed, with spines; basis cranii double; parietal bones meeting on the median line; two nostrils on each side. Gill-membranes free; gills 4; pseudobranchiae present. Vertebrae 25 to 40, the anterior praecaudals with sessile ribs, the posterior with transverse processes. Post-temporal fused with the skull; scapula and coracoid separated by a cartilaginous space; pectoral rays inserted on the scapula and on 4 large plate-like pterygials, of which two are in contact with the coracoid; 2 or 3 of the lower pectoral rays detached, forming feelers. Ventral fins widely separated, with 1 spine and 5 soft rays. Spinous dorsal shorter than the soft; anal without spines. Body covered with scales or bony plates.

Marine fishes from all warm and temperate regions, some occurring in deep water. They are remarkable for the {701}finger-like appendages of the pectoral fins, which are employed to feel the ground in search of crustaceans and other small animals on which they feed; also for the grunting sounds which they utter by the contraction of the air-bladder. About 50 species are known, referable to 4 genera: _Prionotus_, _Trigla_, _Lepidotrigla_, _Peristedion_. Fossil remains referred to _Trigla_ have been found in Miocene and later formations. British species are the Grey Gurnard (_Trigla gurnardus_), the Red Gurnard (_T. cuculus_), the Tub or Sapphirine Gurnard (_T. hirundo_), the Piper (_T. lyra_), the Long-finned Gurnard (_T. obscura_), and the Streaked Gurnard (_T. lineata_).

FAM. 11. DACTYLOPTERIDAE.—Head completely cuirassed; basis cranii simple; parietal bones meeting on the median line; two nostrils on each side. Gill-cleft broadly separated by scaly isthmus; gills 4; pseudobranchiae present. Vertebrae 20-22 (8-9 + 12-13), the first very elongate and formed by the fusion of three or four; ribs sessile, no transverse processes. Post-temporal fused with the skull; no supraclavicle; scapula and coracoid well developed, in contact with each other; pectoral rays divided into two parts, inserted on the scapula and on 4 elongate pterygials, of which 3 are in contact with the coracoid. Ventral fins close together, with 1 spine and 4 soft rays. Spinous dorsal shorter than the soft; anal without spines. Body covered with hard, rough scales.

The "Flying Gurnards," of which four species are known, belonging to a single genus (_Dactylopterus_), are inhabitants of the tropical and warm parts of the Atlantic and the Indian Ocean and Archipelago. They are remarkable, when adult, for the {702}wing-like portion of the pectoral fins, by which they are able to move in the air like _Exocoetus_, but for shorter distances, and, unlike them, the wings are moved rapidly, the mode of flight resembling that of many forms of grasshoppers;[740] the young, however, have comparatively short pectorals, and were formerly regarded as belonging to a distinct genus (_Cephalacanthus_).

DIVISION VIII.—JUGULARES.

No bony stay for the praeoperculum. Ventral fins jugular or mental. Gill-openings in front of the pectoral fin, the base of which is vertical or subvertical.

In a recently published note[741] I have alluded to the group of Physoclistous fishes for which I proposed to revive the old name Jugulares, pointing out that some of the forms previously grouped together as Trachinidae agree with the Gadidae, not only in the jugular position of the ventral fins, but also in the condition of the scapula and coracoid. Mr. Regan[742] has since been able to show that the Gadidae and Macruridae possess certain characters in common by which they may be separated not only from the other Jugulares, but even from the Acanthopterygians, and, as mentioned above (p. 646), the Müllerian Sub-order Anacanthini may be maintained, after excluding the Pleuronectidae. That the Blenniidae are akin to _Lycodes_ and its allies has long been admitted, and authors who have placed them in different divisions of their systems have had to confess the difficulty of referring certain genera to the one family rather than to the other. The fact that _Lycodes_ and many forms previously associated with the Ophidiidae agree with the Macruridae and Gadidae in the diphycercal vertebral column and in the absence of spines to the fins is merely, it seems to me, the result of degradation; they probably form the terminal group of a series in which the vertebral column was originally homocercal and fin-spines were present, as is the case in most of the Blenniidae and Trachinidae and their near allies. All these families may be assumed to have evolved in several series, often on parallel lines, from some group closely related to the {703}Berycidae; and the resemblance which their terminal forms bear to the Anacanthini is, as pointed out by Regan, probably to be ascribed to convergence, not to any close genetic affinity, as hitherto believed by many authors.

The character of the position of the scapular foramen, either in the scapular bone or between it and the coracoid, which obtains in many genera of this division as well as in most of the Anacanthini, has proved to be unreliable even for the purpose of family definition; it is, however, of assistance in determining the relation of certain obscure, degraded forms placed by some authors with the Anacanthines, by others with the Blenniids.

SYNOPSIS OF THE FAMILIES.

I. Pectoral rays attached to the scapula and to a series of pterygials
of which only one or two are in contact with the scapula (see
Fig. 427); ventral fins jugular, with 1 spine and 4 or 5 soft rays;
anterior dorsal rays usually spinous or not articulated, often forming
a detached fin.

A. Epipleurals present.

1. Second suborbital produced inwards to support the eye-ball.

Ventrals close together; scales very small, cycloid, forming
oblique bands 1. _Trachinidae_.

Ventrals widely separated 2. _Percophiidae_.

2. No subocular shelf.

Ventrals widely separated; two nostrils on each side
3. _Leptoscopidae_.

Ventrals widely separated; a single nostril on each side
4. _Nototheniidae_.

Ventrals close together; scales very small, forming oblique bands;
head partly covered with bony plates 5. _Uranoscopidae_.

B. No epipleurals. {704}

Post-temporal forked, articulated to the skull; soft dorsal and anal
much elongate 6. _Trichodontidae_.

Post-temporal closely adnate to the skull; soft dorsal and anal
short (with only 7 to 10 rays) 7. _Callionymidae_.

Post-temporal simple, articulated to the skull; soft dorsal and anal
short; a ventral sucker 8. _Gobiesocidae_.

II. Pectoral rays all attached to the pterygials, of which two or three
are in contact with the scapula; ventral fins, if present, jugular or
mental, composed of 1 to 4 rays.

A. Ventrals jugular or absent.

Post-temporal distinctly forked; praecaudal vertebrae with
transverse processes; some or all of the dorsal rays spinous
or not articulated; caudal fin usually distinct 9. _Blenniidae_.

Post-temporal small and ankylosed to the skull; praecaudal
vertebrae without well-developed transverse processes; a very
short spinous dorsal; caudal fin distinct 10. _Batrachidae_.

Post-temporal distinctly forked; praecaudal vertebrae with haemal
arches; dorsal rays all spinous; caudal fin distinct
11. _Pholididae_.

Post-temporal distinctly forked; praecaudal vertebrae with
transverse processes; dorsal rays all articulated, or a few of
the posterior spinous; no distinct caudal fin 12. _Zoarcidae_.

Post-temporal forked, ankylosed to the skull; praecaudal vertebrae
with transverse processes; no spines; no distinct caudal fin
13. _Congrogadidae_

B. Ventrals mental (just behind the chin); no spines 14. _Ophidiidae_.

III. Pectoral rays attached to an undivided cartilaginous plate
representing the pterygials; ventral fins jugular, reduced to a
filament formed of two adnate rays; fins without spines
15. _Podatelidae_.

FAM. 1. TRACHINIDAE.—Second suborbital with an internal lamina, supporting the globe of the eye; mouth large, protractile. Ribs and epipleurals nearly equally developed, sessile; posterior praecaudal vertebrae with short parapophyses. Gill-membranes free from isthmus; 6 branchiostegal rays; gills 4, a slit behind the fourth; pseudobranchiae well developed. Scapula and coracoid well developed, a foramen between them; pectoral rays attached to the scapula and to three short and broad pterygials, two of which are in contact with the coracoid. Ventral fins jugular, close together, with 1 spine and 5 soft rays. Body elongate, covered with small cycloid scales forming oblique bands. A short spinous dorsal and a long soft dorsal and anal. Vertebrae 35-43 (10-11 + 25-32). No air-bladder.

This family includes but one genus (_Trachinus_), the Weevers, with 4 species, occurring on the coasts of Europe, the {705}Mediterranean, and West Africa north of the Equator. A fossil species has been described from the Upper Miocene of Croatia. The two British species, _T. draco_ and _T. vipera_, are well known for the painful wounds which they are able to inflict through their sharp, grooved dorsal and opercular spines, which convey a very active poisonous fluid secreted by small glands at their base. As these fish like to bury themselves partially in the sands in shallow water, people bathing occasionally tread on them with, as a rule, at least violent pain as a result.[743] The flesh is not bad eating, and great numbers of the larger species (_T. draco_), are brought to the Paris market.

FAM. 2. PERCOPHIIDAE.—_Percophis_, with a single species from the coast of Brazil, differs from the Trachinidae in the scapular fenestra being situated entirely in the scapula, in the ventral fins being rather widely separated at the base, and in the quincuncial disposition of the scales. Vertebrae, 57 (22 + 35). _Bleekeria_ and _Embolichthys_, from the Indian and Japanese seas, with the ventral fins rudimentary or absent, which have been placed in the Ammodytidae, appear to be related to _Percophis_.

FAM. 3. LEPTOSCOPIDAE.—Differ from the preceding in the absence of a subocular shelf. Scapular fenestra either in the scapula or between the scapula and the coracoid. Mostly Marine Fishes, various in form, from the tropics to the Antarctic circle, some occurring at great depths. About 25 species, referable to 7 genera: _Leptoscopus_, _Parapercis_, _Neopercis_, _Pteropsaron_, _Bembrops_, _Pleuragramma_, _Chimarrhichthys_. The latter, from New Zealand, is the only freshwater form of the family, and is remarkably adapted for living in alpine torrents. _Pleuragramma antarcticum_, brought home by the Southern Cross Expedition, comes from 78° 35´ S. lat., the farthest point at which fishes have yet been obtained in the Antarctic region. _Macrius amissus_, from the Pacific Ocean at a depth of 1000 fathoms, which, judging from a very imperfect description, probably belongs to this family, measures 5 feet, and is the largest known deep-sea Teleostean.

FAM. 4. NOTOTHENIIDAE.—Also closely allied to the Trachinidae. No subocular shelf; a single nostril on each side; ventrals {706}widely separated; pectoral arch usually as in the Trachinidae, but scapular fenestra sometimes in the scapula (_Trematomus_). Body varying much in shape according to the genera, the form sometimes suggestive of the Cottidae; scales usually ctenoid, sometimes absent; anterior (spinous) dorsal sometimes absent; lateral line often double, or even triple. Mostly from the Southern seas and the Antarctic circle. About 40 species, referable to 19 genera, of which the following are the principal:—_Notothenia_, _Trematomus_, _Chaenichthys_, _Champsocephalus_, _Cryodraco_, _Acanthaphritis_, _Eleginops_, _Bovichthys_, _Gymnodraco_, _Gerlachia_, _Bathydraco_, _Racovitzaia_, _Harpagifer_, _Draconetta_.

FAM. 5. URANOSCOPIDAE.—Agree with the Trachinidae in general structure, and in the closely approximated ventrals. Scales very small, in oblique bands, or absent. Pterygials much reduced, fused with the scapula and the coracoid; scapular fenestra in the scapula. Parapophyses strongly developed on the praecaudal vertebrae, with the ribs attached to their upper surface. The head is very large, broad, partly covered with bony plates; cleft of the mouth vertical; eyes on the upper surface of the head. Vertebrae 25 to 30 (12-14 + 13-16). Four genera: _Uranoscopus_, _Anema_, _Cathetostoma_, _Ariscopus_, with 15 species, from the tropical seas, northwards to the Mediterranean and Japan, southwards to South Australia and New Zealand.

FAM. 6. TRICHONOTIDAE.—Small elongate fishes very nearly related to the Callionymidae, with which they agree in the arrangement of the bones at the base of the pectoral fins and the absence of epipleurals; but post-temporal more distinctly forked and detached from the skull, suborbital arch ossified (without subocular shelf), gill-openings wide, a single long dorsal fin, a long anal fin, and body covered with scales. Vertebrae 48-53. Five marine species, referable to 3 genera: _Trichonotus_ and _Taeniolabrus_ from the Indian Ocean, and _Hemerocoetes_ from New Zealand.

FAM. 7. CALLIONYMIDAE.—Suborbital arch ligamentous; entopterygoid absent; basis cranii simple; mouth rather small, protractile. Vertebrae few (7 + 14), the last two much enlarged; most of the vertebrae with bifid neural processes, simulating a "spina bifida"; first vertebra ribless,[744] second to fourth {707}with sessile ribs and no transverse processes, fifth to seventh with ribs inserted on short transverse processes; no epipleurals. Post-temporal forked, but completely adnate to the skull; scapula separated from the coracoid by a fenestra; pectoral rays attached to the scapula and to three broad pterygials, all three in contact with the coracoid. Ventral fins jugular, widely separated from each other, with 5 soft rays in addition to a short spine. Gill-openings very narrow, generally reduced to a foramen on the upper side of the operculum; 6 branchiostegal rays; gills 4, a slit behind the fourth; pseudobranchiae well developed. Body naked. Two dorsal fins, the first composed of a few flexible spines; second dorsal and anal rather short (7-10 rays).

Small marine fishes, referable to 2 genera; _Callionymus_, with about 45 species, nearly cosmopolitan, and _Vulsus_, with a single species from Amboyna and Celebes. In the common British species, the Dragonet (_Callionymus lyra_), the male acquires very marked secondary characters, the snout becoming more elongate, the second dorsal fin much produced, and the body ornamented with yellow and blue bands. The courtship and pairing have been described by E. W. L. Holt,[745] who observes that this curious fish offers the only instance of a definite sexual intercourse among Teleosteans propagating by pelagic ova. In the Indian _C. carebares_ it is the female that is the more brightly coloured.

FAM. 8. GOBIESOCIDAE.—Suborbital arch absent; entopterygoid absent; basis cranii simple; mouth moderate, protractile. Vertebrae numerous, 27-31 (14-16 + 11-21), the first, if present, rudimentary,[746] the third and following praecaudals with long parapophyses[747] bearing the ribs at their extremity; no epipleurals. Post-temporal simple, articulated to the skull; scapula with a foramen, coracoid much reduced; pectoral rays inserted on the scapula and on four large pterygials, two of which are in contact with the scapula; an adhesive ventral disk, simple or double, supported in front by the clavicles, in the {708}middle and at the sides by the enlarged pelvic bones and fins, and behind by the enlarged lamellar post-clavicles, which are formed of two pieces. Ventral fins jugular, widely separated from each other, formed of 1 short spine and 4 or 5 soft rays. Gill-openings narrow; 5 or 6 branchiostegal rays; gills 3 or 3½; pseudobranchiae well developed. Body naked. Dorsal and anal fins short, composed entirely of soft branched rays.

First placed with the Acanthopterygians by J. Müller, notwithstanding the absence of spinous rays in the vertical fins, and removed from the vicinity of the Cyclopteridae by Günther, raised to the rank of a Sub-order (Xenopteri) near the Anacanthini by Gill, the exact systematic position of this curious type of Fishes has long been a matter of uncertainty. The position of the ventral fins suggests, at first glance, affinity with the Callionymidae, and a comparison of the skeletons of these two types has convinced me that they are really related to each other, although both highly modified in different directions.

The Cling-Fishes are curious small, carnivorous, Marine Fishes, usually found between tide-marks among loose stones and shells, to which they adhere firmly by means of the adhesive ventral disk. They can live a long time out of water. About 50 species are known, from various parts of the world, extending as far north as Scotland and Vancouver Island, and southwards to {709}New Zealand. Three or four species, belonging to the genus _Lepadogaster_, are known to occur on the British coasts. The principal genera are _Gobiesox_, _Chorisochismus_, _Sicyases_, _Cotylis_, _Lepadogaster_, _Trachelochismus_, _Diplocrepis_, _Crepidogaster_, and _Leptopterygius_.[748]

FAM. 9. BLENNIIDAE.—Suborbitals often forming a more or less distinct subocular shelf; mouth moderate or large, more or less protractile, often bordered to a considerable extent by the maxillaries. Most of the praecaudal vertebrae with strong transverse processes supporting the ribs, which may bear epipleurals. Gill-membranes usually attached to isthmus; 6 or 7 branchiostegal rays; gills 4, a slit behind the fourth; pseudobranchiae usually present. Post-temporal forked; scapula and coracoid more or less developed, sometimes much reduced, the former pierced by a foramen; pectoral rays attached to 4 or 5 hour-glass-shaped pterygials, one or two of which are in contact with the coracoid. Ventral fins jugular, with not more than 4 rays, or absent. Body more or less elongate, sometimes Eel-shaped, naked or with small scales. Dorsal and anal fins elongate, the former constituted entirely of spines, or anteriorly of spines or non-articulated rays, and posteriorly of soft rays. Caudal fin usually distinct, with expanded hypural.

A large family, mostly of small Marine Fishes, the arrangement of which still offers great difficulties. Whether the aberrant genera _Cerdale_ and _Ptilichthys_ deserve to be regarded as the types of distinct families cannot be decided until the skeleton has been examined. The species number about 350, from nearly all the seas, a few inhabiting fresh waters, and are referred to numerous genera, of which the following are the principal:—_Gadopsis_, _Enneanectes_, _Heterostichus_, _Acanthoclinus_, _Clinus_, _Emmnion_, _Blennius_, _Chasmodes_, _Petroscirtes_, _Xiphasia_, _Anarrhichas_, _Pataecus_, _Salarias_, _Ophioblennius_, _Anoplarchus_, _Xiphistes_, _Opisthocentrus_, _Chaenopsis_, _Pholedichthys_, _Lumpenus_. Remains of _Clinus_ and _Blennius_ have been described from the Miocene, and the extinct genus _Pterygocephalus_, from the Upper Eocene, is regarded as allied to _Clinus_.

The Blenniidae are mostly carnivorous, but a few are herbivorous; some are viviparous (_Clinus_), others oviparous. Species {710}of _Blennius_ occur in abundance on our coasts, and are among the most familiar tenants of small rock-pools. Their habits have been admirably described by Guitel.[749] The male makes a sort of nest, and defends the brood. Numerous species of the genus _Salarias_ occur in the tropics; these little fish, as their name implies, are remarkable for the long leaps they are able to make. The largest of the Blenniids are the "Wolf-Fishes," often named "Cat-Fishes" (_Anarrhichas_), of which one species (_A. lupus_) is common on the British coasts, growing to a length of 5 or 6 feet. "It is impossible," says Brown Goode, "to imagine a more voracious-looking animal than the Sea Cat-Fish, with the massive head and long sinuous, muscular body, its strongly rayed fins, its vice-like jaws, armed with great pavements of teeth, those in front long, strong, pointed, like those of a tiger. It has been known to attack furiously persons wading at low tide among the rock-pools." Its flesh is excellent eating, but generally despised in this country owing to the unprepossessing appearance of the animal.

FAM. 10. BATRACHIDAE.—Suborbital arch absent; basis cranii simple; mouth very large, slightly protractile, bordered to a great extent by the maxillaries. Vertebrae numerous, 29-46 (11-12 + 17-34), without ribs, with sessile epipleurals, simulating ribs;[750] parapophyses rudimentary or absent. Post-temporal small and ankylosed to the skull; scapula and coracoid much reduced, 4 or 5 elongate pterygials, dilated distally, the two lower in contact with the coracoid. Ventral fins jugular, with 1 spine and 2 or 3 branched rays. Gill-openings narrow, the gill-membranes broadly grown to the isthmus; gills 3; pseudobranchiae absent. Head broad and depressed; body naked or with small scales. Spinous dorsal very short, soft dorsal and anal long.

This family is on the whole intermediate between the Blenniidae and the Pediculati. Sluggish, voracious, carnivorous Fishes from the shores of tropical and warm seas, some of them ascending rivers. The species number about 20, referable to {711}5 genera: _Batrachus_, _Opsanus_, _Thalassophryne_, _Thalassothia_, and _Porichthys_. The eggs of _Batrachus tau_ are very large, ¼ inch in diameter, and are deposited in a little retreat provided by the parent; the male assumes the care of the brood; the young fasten themselves to rocks by means of an adhesive ventral disk, which soon disappears.[751]

In _Thalassophryne_, from the coasts of Central America, the opercular spine and the two dorsal spines are perforated, and convey poison from subcutaneous sacs situated at their base.[752] In the American genus _Porichthys_ the head and body bear series of greatly developed mucous pores, some of which simulate the photophores of _Scopelus_, but are not luminous.[753]

FAM. 11. PHOLIDIDAE.—Suborbitals not forming a subocular shelf; mouth scarcely protractile, with thick lips. Praecaudal vertebrae similar to the caudals, without transverse processes, with hæmal arches; ribs sessile. Gill-membranes free from the isthmus; 4 or 5 branchiostegal rays; gills 4, a slit behind the fourth; pseudobranchiae present. Scapular arch as in Blenniidae. Ventral fins jugular and rudimentary, or absent. Body elongate, compressed, with very small scales. Dorsal and anal fins elongate, the former constituted entirely of non-articulated rays or spines. Caudal fin distinct, with expanded hypuraL.

Small shore fishes of the Northern Seas, differing from the Blenniidae in the structure of the praecaudal vertebrae, in spite of the external resemblance which the two known genera, _Pholis_ (_Centronotus_) and _Apodichthys_, bears to _Anoplarchus_ and _Xiphistes_. Species about 10.

{712}A well-known British fish of this family is the little Gunnel or Butter-Fish (_Pholis gunnellus_), remarkable for the manner in which the female protects her offspring, coiling herself round the eggs, which she rolls up into a ball about the size of a Brazil nut, in holes of the boring Mollusc (_Pholas_). The male sometimes assists the female.

FAM. 12. ZOARCIDAE.—Suborbitals not forming a subocular shelf; mouth feebly protractile. Praecaudal vertebrae with strong transverse processes bearing ribs and epipleurals. Gill-membranes usually more or less broadly united to isthmus; 5 to 8 branchiostegal rays; gills 4, a slit behind the fourth; pseudobranchiae present or absent. Scapular arch as in Blenniidae. Ventral fins jugular or absent; if present, with 1 to 4 rays. Body more or less elongate, naked or with very small scales. Dorsal and anal fins elongate, all the rays articulated, or a few of the posterior dorsals spinous. Usually no distinct caudal fin.

These fishes have usually been placed, in part at least, near the Gadids, but they have more in common with the Blenniids, as pointed out by Jordan and Evermann, and may be regarded as degraded forms descended from the latter.[754] The family is widely distributed in all seas, many of the forms being specially adapted to live at great depths. The species known number about 130. Principal genera: _Scytalina_, _Zoarces_, _Lycodes_, _Gymnelis_, _Lycocara_, _Melanostigma_, _Derepodichthys_, _Bathyonus_, _Porogadus_, _Bythitis_, _Neobythitis_, _Cataetyx_, _Selachophidium_, _Acanthonus_, _Typhlonus_, _Aphyonus_, _Tauredophidium_, _Rhodichthys_, _Brosmophycis_, _Brotula_, _Lucifuga_, _Lamprogrammus_, _Diplacanthopoma_, _Hephthocara_.

{713}Some are oviparous, others (_Zoarces_, _Diplacanthopoma_, _Hephthocara_, _Lucifuga_) viviparous. The eyes are absent, or at least not visible externally in some of the bathybial forms (_Typhlonus_, _Aphyonus_, _Tauredophidium_), as well as in the only known freshwater forms, the Cuban Cave-Fishes _Stygicola_ and _Lucifuga_, which are evidently allied to the marine _Brotula_, whilst the blind Cave-Fishes of North America (cf. p. 618) are derived from freshwater types. It is believed that blind fishes are found also in caves of the island of Jamaica, but no specimens have been seen by naturalists. The largest Cuban Cave-Fish is 5 inches long.[755]

FAM. 13. CONGROGADIDAE.—Eel-shaped Fishes without ventrals, allied to the Blenniidae, but with all the rays soft and articulated, the post-temporal small and ankylosed to the skull, and the sub-orbitals produced into laminae supporting the eyeball. Lips much developed; gill-membranes free from isthmus; scales very small.

A single genus, _Congrogadus_, with three species from the Australian and East Indian coasts. The recently described Japanese genus _Hierichthys_ has been referred to this family.

FAM. 14. OPHIDIIDAE.—Degraded Blenniids, closely related to the Zoarcidae, with pseudobranchiae, with tapering tail without distinct caudal fin, and with the ventral fins each reduced to a pair of filaments or a bifid ray inserted just behind the chin at the extremity of the clavicle, which is produced forwards as a slender rod.

Small marine, carnivorous fishes, from the Atlantic and Southern Pacific coasts as well as from great depths in the Atlantic, Pacific, and Indian Oceans. About 25 species are known. Genera: _Ophidium_, _Lepophidium_, _Genypterus_.

FAM. 15. PODATELIDAE.—Mouth inferior, protractile, toothless or with minute teeth. Praecaudal vertebrae with transverse processes, to which the ribs are attached. Gill-membranes narrowly attached to isthmus; 8 or 9 branchiostegal rays; gills 4; no pseudobranchiae. Supratemporal loosely attached by ligament to the skull; scapula cartilaginous, perforate, bearing the base of the pectoral fin, which is an undivided cartilaginous plate; coracoid small, ossified. Ventral fins jugular, each reduced to a single stout filament made up of two intimately coherent rays. Body short, tail elongate and tapering, {714}compressed; no scales. A short dorsal fin, without spines, situated above the pectorals; a long anal fin, continuous with the caudal.

The genus _Podateles_ (_Ateleopus_) comprises only two species from the deep sea, one from Japan and one from India.

DIVISION IX.—TAENIOSOMI.

Exceedingly compressed, more or less elongate, often ribbon-like fishes of doubtful affinities, probably related to the earlier Acanthopterygians, the ventral fins, when well developed, comprising as many as 7 to 9 rays. Dorsal fin extending from the head to the end of the tail, its rays simple (separable into lateral halves), the anterior often prolonged; anal fin very short or absent. Pectoral fin with horizontal or nearly horizontal base, the rays supported by the scapula and by three short pterygials, all three, or two at least, of which are related to the coracoid. Ribs small and slender, or absent. Post-temporal simple and solidly attached to the skull. Scales minute or absent.

Deep-sea or pelagic fishes from the Atlantic and Mediterranean and from the Pacific; the life-histories are still very imperfectly known, and great changes of form take place with growth. Only two families.[756]

{715}FAM. 1. TRACHYPTERIDAE.—Mouth very protractile; ventral fins more or less developed, with 6 to 9 rays, or reduced to a single long ray; no anal fin; vent about the middle of the body; caudal rays, if present, divided into two fascicles, the upper sometimes much prolonged and directed upwards.

Two genera. The most generalised is _Trachypterus_, of which probably only 10 forms are entitled to specific distinction. The best known species is _T. arcticus_, the Deal-Fish or Northern Ribbon-Fish, which reaches a length of 8 feet or more, and of which a few specimens have been stranded on the coasts of Scotland. Nilsson, who has observed these fishes alive on the Scandinavian coast, says they approach the shore at flood-tide on sandy shelving bottoms, and are often left by the retreating waves; that they move with one side turned obliquely upward, and that they lie on the side like Flat-Fishes on the bottom in 2 or 3 fathoms of water. _Regalecus_ differs in the presence of a single ray to the ventral and the absence of the caudal fin. Some 5 or 6 species may be distinguished. _R. glesne_, the Oar-fish, or "King of the Herrings," is the best known and the largest species, reaching a length of over 20 feet. About 25 {716}specimens are known to have occurred on the British coasts. Some of the accounts of "Sea-Serpents" are probably based on this fish, which has been observed to swim with undulating motion and with a small portion of the head as well as the crest-like anterior part of the dorsal fin above the water.

The fish named _Stylophorus chordatus_, which has been referred to this family, is known from a single specimen too imperfectly preserved to afford a clear idea of its affinities.

FAM. 2. LOPHOTIDAE.—Mouth moderately protractile; ventrals very small, if distinct, with 4 or 5 rays; abdominal cavity extending nearly the whole length of the much elongated body, the vent very far back and followed by a short anal fin; caudal fin small, not divided.

A single genus, _Lophotes_, with 3 or 4 species, from the Mediterranean, the tropical Atlantic, the Cape of Good Hope, Japan, and New Zealand, reaching a length of 6 feet or more. The dorsal fin commences with an extremely long and strong spine on the head, which is much elevated and truncate in front.

SUB-ORDER 11. OPISTHOMI

Air-bladder without open duct. Opercle well developed, hidden under the skin; supraoccipital in contact with the frontals, separating the parietals. Pectoral arch suspended from the vertebral column, far behind the skull; no mesocoracoid. Vertical fins with spines. Ventral fins absent.

This division stands in the same relation to the Acanthopterygii as do the Apodes to the Malacopterygii. The single family is possibly derived from the Blenniidae.

FAM. 1. MASTACEMBELIDAE.—Body more or less Eel-shaped; a series of short spines detached from the very elongate dorsal fin, which is more or less confluent with the likewise very elongate anal fin. A single nostril on each side. Mouth not protractile, bordered by the praemaxillaries, to the upper border of which the maxillaries are attached. Gill-cleft inferior; gills 4; branchiostegal rays 6; no pseudobranchiae. Vertebrae numerous (72-95), the praecaudals with transverse processes bearing the ribs. Scales very small.

Carnivorous fishes, from fresh and brackish waters of Southern Asia and Tropical Africa. 33 species are known, referable to {717}two genera: _Mastacembelus_ and _Rhynchobdella_. The largest species reach a length of three feet. Little is known of their habits. Of the Indian _Rhynchobdella aculeata_, Day says it conceals itself in the mud and becomes drowned in water if unable to reach the surface, as it apparently requires to respire air directly.

SUB-ORDER 12. PEDICULATI.

Air-bladder without open duct. Opercle large, hidden under the skin; supraoccipital in contact with the frontals, separating the parietals. Pectoral arch suspended from the skull; no mesocoracoid. No ribs, no epipleurals. Ventral fins jugular. Gill-opening reduced to a foramen situated in or near the axil, more or less posterior to the base of the pectoral. Body naked or covered with spines or bony tubercles.

A small, natural group, connected with the Acanthopterygii Jugulares through the Batrachidae, in which the elongate pterygials of the pectoral fin foreshadow the kind of arm ("pseudobrachium") which is more or less characteristic of these highly aberrant Fishes. As in the Batrachidae, the post-temporal is flat and ankylosed to the cranium, and the suprascapula is much elongated. The pterygials, two or three in number, are separated from the small scapula and coracoid by a broad ligament, the arm-like pectorals being more or less distinctly geniculated and inserted far back behind the cranium. The head is large, the basis cranii simple. The gills are reduced to 2, 2½, or 3. The spinous dorsal, if present, consists of a few rays, which may be modified into tentacles inserted on the head. Vertebrae 17 to 31.

{718}Five families:—

I. Gill-opening in or behind lower axil of pectoral; mouth large,
terminal or directed upwards.

Pectoral fin scarcely geniculated; ventrals present 1. _Lophiidae_.

Pectoral fin scarcely geniculated; ventrals absent 2. _Ceratiidae_.

Pectoral fin strongly geniculated; ventrals present 3. _Antennariidae_.

II. Gill-opening behind lower axil of pectoral; mouth large, inferior;
ventrals absent 4. _Gigantactinidae_.

III. Gill-opening above axil of pectoral; mouth rather small,
subterminal or inferior; pectoral fin strongly geniculated; ventrals
present; spinous dorsal absent or reduced to a small tentacle lodged
in a cavity under the snout 5. _Malthidae_.

FAM. 1. LOPHIIDAE.—Mouth extremely large, terminal, with very strong cardiform teeth. Gill-opening in lower axil of pectoral; pseudobranchiae present. Pectoral fin scarcely geniculated, with two pterygials. Ventral fin with 1 spine and 5 branched rays. Spinous dorsal present. Skin naked.

Twelve species, referable to three genera (_Lophius_, _Chirolophius_, and _Lophiomus_) living on the bottom of the Atlantic, Indian, and Pacific Oceans, at moderate or great depths. _Lophius_ was represented in the Upper Eocene of Monte Bolca.

The Fishing-Frog or Angler (_Lophius piscatorius_) has a wide distribution, occurring on the coasts of Europe and North America. The first dorsal ray, inserted on the snout, is very long, movable in every direction, and terminates in a dermal flap, which is supposed to be used by the "Angler" as a bait, attracting other fishes, which are soon ingulfed in the enormous gape. It grows to a length of over 5 feet. The ventral rays are very elongate in the young.

{719}FAM. 2. CERATIIDAE.—Mouth extremely large, terminal, with strong cardiform teeth. Gill-opening in lower axil of pectoral; pseudobranchiae absent. Pectoral fin scarcely geniculated, with three pterygials. Ventral fins absent. Spinous dorsal fin usually present, sometimes reduced to a single tentacle on the snout. Skin naked.

The members of this family, about 25 in number, are all inhabitants of great depths (300-2600 fathoms). The colour of the body is usually a deep black, and the first dorsal spine, on the head, may terminate in a luminous bulb with or without filaments. "The Bathybial Sea-devils," writes Günther, "are degraded forms of _Lophius_; they descend to the greatest depths of the ocean. Their bones are of an extremely light and thin texture, and frequently other parts of their organisation, their integuments, muscles, and intestines are equally loose in texture when the specimens are brought to the surface. In their habits they probably do not differ in any degree from their surface representative, _Lophius_."

Principal genera: _Ceratias_, _Aceratias_, _Oneirodes_, _Himantolophus_, _Aegaeonichthys_, _Melanocetus_, _Liocetus_, _Linophryne_, _Caulophryne_, _Dolopichthys_.

{720}FAM. 3. ANTENNARIIDAE.—Mouth large, vertical or very oblique, turned upwards, with cardiform teeth. Gill-opening in or behind lower axil of pectoral; pseudobranchiae absent. Pectoral fin forming an elbow-like angle, with three pterygials. Ventral with 4 or 5 rays. Spinous dorsal present. Skin naked or spinulose.

About 40 species, referable to 5 genera: _Pterophryne_, _Antennarius_, _Brachionichthys_, _Saccarius_, and _Chaunax_.

The species of _Antennarius_ live mostly in coral groves, where they lie in wait for prey, well concealed by their protective coloration and the harmonising aspect of their integument and appendages. To this genus also belongs the "Marbled Angler" (_A. marmoratus_), carried about in mid ocean among the _Sargassum_ weed, to rest on which, from its peculiar arm-like pectoral fins, it is specially fitted; there it makes its wonderful nest of silk-like fibres, probably secreted by the parent as in the Sticklebacks, with large bundles of eggs hanging like grape clusters.[757] The deep-sea _Chaunax_ inflates its abdomen like _Tetrodon_.

FAM. 4. GIGANTACTINIDAE.—Mouth inferior, snout produced into a long tentacle directed forwards, and bearing a luminous organ. Body covered with small spines. Otherwise as in the Ceratiidae. _Gigantactis vanhoeffeni_, of Brauer, from the Indian Ocean, at depths of about 1000 fathoms.

FAM. 5. MALTHIDAE.—Mouth rather small, subterminal or inferior, with villiform or cardiform teeth. Gill-opening above pectoral; pseudobranchiae absent. Pectoral fin forming an elbow-like angle, with three pterygials. Ventral with 5 rays. Spinous dorsal absent, or reduced to a more or less developed tentacle lodged in a cavity under the snout. Head and body with bony tubercles or spines.

About 30 species are known, mostly from the deep sea within the tropics (down to 1270 fathoms). Principal genera: _Coelophrys_, _Malthe_, _Malthopsis_, _Halieutaea_, _Halicmethes_, _Dibranchus_.

The "Bat-Fish" (_Malthe vespertilio_), common in shallow water about the West Indies, is said to assume an almost toad-like attitude on the ground, the head being directed slightly upwards, while the pectorals take on the function of hind legs and the ventrals of fore legs.

{721}SUB-ORDER 13. PLECTOGNATHI.

Air-bladder without open duct. Opercular bones more or less reduced; supraoccipital in contact with the frontals, separating the parietals; maxillary and praemaxillary bones often firmly united. Pectoral arch suspended from the skull. No ribs. Ventral fins thoracic and much reduced if present; the pelvic bones, if present, more or less completely co-ossified. Gill-opening much reduced. Body covered with more or less osseous scales, bony scutes, or spines, or naked.

A highly aberrant group, closely connected with the Acanthopterygii through the Acanthuridae, as pointed out long ago by Dareste.[758] The skeleton is often feebly ossified and the vertebrae much reduced in number, but the jaws, although short, are very strong, usually with large sectorial teeth which may be confluent into a beak; the post-temporal is short and simple, suturally united to the squamosal. These fishes have usually been arranged in three divisions: _Sclerodermi_, _Ostracodermi_, and _Gymnodontes_, but Regan,[759] whose classification is here followed, has shown that the latter include a type (_Triodon_) which, in spite of its beak-like teeth, is more nearly related to the Sclerodermi, whilst the Ostracodermi have much more in common with the latter than with the Gymnodontes. It therefore appears best to admit only two divisions, the first with 4, the second with 3 families:—

I. SCLERODERMI.—Supraclavicle vertical; pectoral arch of the
Perciform type; all the vertebrae with a single neural spine.

A. Body covered with hard or spinous scales; epipleurals present;
pelvis present.

Teeth separate; spinous dorsal present; ventrals paired; pelvis
immovable 1. _Triacanthidae_.