Fig. 297.—Gonorhynchus greyi.
Fig. 298.—Scale of Gonorhynchus greyi.
One genus and species only (Gonorhynchus greyi) is known; it is a semi-pelagic fish, not very rare off the Cape of Good Hope, and in the Australian and Japanese seas. From 12 to 18 inches long. The colonists in New Zealand name it “Sand-eel,” as it frequents bays with sandy bottom. It is eaten.
Body covered with cycloid scales; head naked; barbels none. Margin of the upper jaw formed by the intermaxillaries mesially, and by the maxillaries laterally, the latter being articulated to the end of the former. Opercular apparatus complete. Adipose fin none; the dorsal fin belongs to the caudal portion of the vertebral column. Stomach horseshoe-shaped, without blind sac; intestine short; one pyloric appendage. Pseudobranchiæ none; air-bladder simple. Gill-openings wide. The ova fall into the abdominal cavity before exclusion.
One genus and species only (Hyodon tergisus) is known, generally called “Moon-eye.” It is abundant in the western streams and great lakes of North America. From 12 to 18 inches long.
Body covered with large cycloid scales; sides of the head osseous. Margin of the upper jaw formed by the single intermaxillary mesially, and by the maxillaries laterally. The dorsal fin belongs to the caudal portion of the vertebral column, is short, opposite and similar to the anal. Gill-openings wide; gill-covers consisting of a præoperculum and operculum only. Branchiostegals numerous. Pseudobranchiæ none; air-bladder simple. Stomach without coecal sac; one pyloric appendage. Sexual organs with a duct.
A small freshwater-fish (Pantodon buchholzi), singularly alike to a Cyprinodont, from the west coast of Africa.
Body covered with large hard scales, composed of pieces like mosaic. Head scaleless; its integuments nearly entirely replaced by bone; lateral line composed of wide openings of the mucus-duct. Margin of the upper jaw formed by the intermaxillaries mesially, and by the maxillaries laterally. The dorsal fin belongs to the caudal portion of the vertebral column, is opposite and very similar to the anal fin; both approximate to the rounded caudal (with which they are abnormally confluent). Gill-openings wide; pseudobranchiæ none; air-bladder simple or cellular. Stomach without coecal sac; pyloric appendages two.
Large freshwater-fishes of the tropics, whose singular geographical distribution has been noticed above (p. 223).
Osteoglossum.—Cleft of the mouth very wide, oblique, with the lower jaw prominent. A pair of barbels at the lower jaw. Abdomen trenchant. Bands of rasp-like teeth on the vomer, palatine and pterygoid bones, on the tongue and hyoid. Pectoral fins elongate.
O. bicirrhosum from Brazil and Guyana, O. formosum from Borneo and Sumatra, O. leichardti from Queensland.
Arapaima.—Cleft of the mouth wide, with the lower jaw prominent; barbels none. Abdomen rounded. Jaws with an outer series of small conical teeth; broad bands of rasp-like teeth on the vomer, palatines, pterygoids, sphenoid, os linguale, and hyoid. Pectoral fins of moderate length.
Fig. 299.—Arapaima gigas.
The largest freshwater Teleostean known, exceeding a length of 15 feet and a weight of 400 pounds. It is common in the large rivers of Brazil and the Guyanas, and esteemed as an article of food. When salted it is exported in large quantities from the inland fisheries to the seaports.
Heterotis.—Cleft of the mouth rather small, with the jaws subequal; barbels none. A single series of small teeth in the jaws; pterygoids and hyoid with a patch of small conical teeth; none on the vomer or palatines.
This fish (H. niloticus), which is not uncommon in the Upper Nile and the West African rivers, exhibits several anatomical peculiarities. The fourth branchial arch supports a spiral accessory organ, the function of which is still unexplained. The air-bladder is cellular, and the stomach consists of a membranous and a muscular portion.
Body covered with scales; head naked; barbels none. Abdomen frequently compressed into a serrated edge. Margin of the upper jaw formed by the intermaxillaries mesially, and by the maxillaries laterally; maxillaries composed of at least three movable pieces. Opercular apparatus complete. Adipose fin none. Dorsal not elongate; anal sometimes very long. Stomach with a blind sac; pyloric appendages numerous. Gill-apparatus much developed, the gill-openings being generally very wide. Pseudobranchiæ generally present. Air-bladder more or less simple.
The family of “Herrings” is probably unsurpassed by any other in the number of individuals, although others comprise a much greater variety of species. The Herrings are principally coast-fishes, or, at least, do not go far from the shore; none belong to the deep-sea fauna; scarcely any have pelagic habits, but many enter or live in fresh waters communicating with the sea. They are spread over all the temperate and tropical zones. Fossil remains of Herrings are numerous, but the pertinence of some of the genera to this family is open to serious doubts, as the remains are too fragmentary to allow of determining whether they belong to Salmonoids or Clupeoids. Therefore, Agassiz comprised both families in one—Halecidæ. Many of the remains belong to recent genera, which are readily recognised, as Clupea, Engraulis and Chanos, principally from the schists of Glaris and Licata, from Monte Bolca and the Lebanon. Others, like Thrissopater, from the Gault at Folkestone, Leptosomus, Opisthopteryx, Spaniodon, from the chalk and tertiary formations, can be readily associated with recent genera. But the majority do not show an apparent affinity to the present fauna. Thus, Halec from the chalk of Bohemia, Platinx and Coelogaster from Monte Bolca, Rhinellus from Monte Bolca and Mount Lebanon, Scombroclupea, with finlets behind the anal, from the Lebanon and Comen, and Crossognathus from tertiary Swiss formations, allied to Megalops, Spathodactylus from the same locality, and Chirocentrites from Mount Lebanon, etc. Finally, a genus recently discovered in tertiary formations of Northern Italy, Hemitrichas, has been classed with the Clupeoids, from which, however, it differs by having two short dorsal fins, so that it must be considered, without doubt, to be the representative of a distinct family.
Engraulis (including Cetengraulis).—Scales large or of moderate size. Snout more or less conical, projecting beyond the lower jaw. Teeth small or rudimentary. Intermaxillaries very small, hidden; maxillary long, attached to the cheek by a scarcely distensible membrane. Anal fin of moderate or great length. Branchiostegals short, from nine to fourteen in number.
Not less than forty-three different species of “Anchovies” are known from temperate and tropical seas. They exhibit marked differences in the length of their maxillary bone, which sometimes does not reach the gill-opening, whilst in other species it extends far beyond it; and in the number of their anal rays, which varies from 20 to 80. Some have the upper pectoral ray prolonged into a filament, thus leading towards the succeeding genus, Coilia. The majority are recognised, besides, by their peculiar structure, by a broad silvery, lateral band, similar to that observed in the Atherines. The most celebrated Anchovy is E. encrasicholus, very plentiful in the Mediterranean, but rarely wandering northwards. It is the species which, preserved in salt, is exported to all parts of the world, although similarly lucrative fisheries of Anchovies might be established in Tasmania where the same species occurs, in Chile, China, Japan, California, at Buenos Ayres, each of which countries possesses Anchovies by no means inferior to the Mediterranean species.
Coilia.—Body terminating in a long tapering tail. Scales of moderate size. Snout and jaws as in Engraulis. Anal fin exceedingly long, confluent with the caudal. The two or three upper pectoral rays are much prolonged, and their branches form four, six, or seven filaments.
Fig. 300.—Coilia clupeoides.
Ten species from Indian and Chinese seas.
Chatoëssus.—Body compressed; abdomen serrated. Scales of moderate size. Snout obtuse, or obtusely conical, more or less projecting beyond the cleft of the mouth, which is narrow, more or less transverse. Maxillary joined to the ethmoid, its upper portion being behind the intermaxillary. Teeth none. Anal fin rather long; dorsal opposite to the ventrals, or to the space between ventrals and anal. Gill-membranes entirely separate; branchial arches forming two angles, one pointing forward and the other backwards; the fourth branchial arch with an accessory organ; branchiostegals of moderate length, five or six in number.
Ten species from the coasts, brackish and fresh waters of Central America (one species ranges to New York), Australia, the East Indies, and Japan.
Clupea.—Body compressed, with the abdomen serrated, the serrature extending forwards to the thorax. Scales of moderate or large, rarely of small size. Upper jaw not projecting beyond the lower. Cleft of the mouth of moderate width. Teeth, if present, rudimentary and deciduous. Anal fin of moderate extent, with less than thirty rays; dorsal fin opposite to the ventrals. Caudal forked.
This genus comprises more than sixty different species, the geographical distribution of which coincides with that of the family. The majority are of greater or less utility to man, but a few tropical species (C. thrissa, C. venenosa, and others) acquire, probably from their food, highly poisonous properties, so as to endanger the life of persons eating them. The most noteworthy species are—
1. C. harengus (the “Herring”).—It is readily recognised by having an ovate patch of very small teeth on the vomer. D. 17–20. A. 16–18. L. lat. 53–59. Vert. 56. Gill-cover smooth, without radiating ridges. It inhabits, in incredible numbers, the German Ocean, the northern parts of the Atlantic, and the seas north of Asia. The Herring of the Atlantic coasts of North America is identical with that of Europe. A second species has been supposed to exist on the British coast (C. leachii), but it comprises only individuals of a smaller size, the produce of an early or late spawn. Also the so-called “White-bait” is not a distinct species, but consists chiefly of the fry or the young of herrings, and is obtained “in perfection” at localities where these small fishes find an abundance of food, as in the estuary of the Thames.
[Separate accounts on the Herring may be found in Cuvier and Valenciennes, “Hist. nat. des Poissons,” vol. xx.; J. M. Mitchell, “The Herring, its Natural History and National Importance,” Edinb. 1864, 8vo; P. Neucrantz, “De Harengo,” Lübeck, 1654; J. S. Dodd, “Essay towards a Natural History of the Herring,” Lond. 1768, 8vo; Bock, “Versuch einer vollstændigen Natur-und Handels-Geschichte des Hærings,” Königsberg, 1769, 8vo.]
2. C. mirabilis.—The Herring of the North Pacific.
3. C. sprattus.—The “Sprat.” Without vomerine teeth. D. 15–18. A. 17–20. L. lat. 47–48. Vert. 47–49. Gill-cover, smooth, without radiating ridges. Abundant on the Atlantic coasts of Europe.
4. C. thrissa.—One of the most common West Indian fishes, distinguished by the last dorsal ray being prolonged into a filament. Hyrtl has discovered a small accessory branchial organ in this species.
5. C. alosa.—The “Shad” or “Allice Shad,” with very fine and long gill-rakers, from 60 to 80 on the horizontal part of the outer branchial arch, and with one or more black lateral blotches. Coasts of Europe, ascending rivers.
6. C. finta.—The “Shad” or “Twaite Shad,” with stout osseous gill-rakers, from 21 to 27 on the horizontal part of the outer branchial arch, and spotted like the preceding species. Coasts of Europe, ascending rivers, and found in abundance in the Nile.
7. C. menhaden.—The “Mossbanker,” common on the Atlantic coasts of the United States. The economic value of this fish is surpassed in America only by that of the Gadoids, and derived chiefly from its use as bait for other fishes, and from the oil extracted from it, the annual yield of the latter exceeding that of the whale (from American Fisheries). The refuse of the oil factories supplies a material of much value for artificial manures.
[See G. Brown Goode, “The Natural and Economical History of the American Menhaden,” in U.S. Commission of Fish and Fisheries, Part V., Washington, 1879, 8vo.]
8. C. sapidissima.—The American Shad, abundant, and an important food-fish on the Atlantic coasts of North America. Spawns in fresh water.
9. C. mattowocca.—The “Gaspereau” or “Ale-wife,” common on the Atlantic coasts of North America, ascending into freshwater in early spring, and spawning in ponds and lakes.
10. C. pilchardus.—The “Pilchard” or the “Sardine,” equally abundant in the British Channel, on the coast of Portugal, and in the Mediterranean, and readily recognised by radiating ridges on the operculum, descending towards the sub-operculum.
11. C. sagax.—Representing the Pilchard in the Pacific, and found in equally large shoals on the coasts of California, Chile, New Zealand, and Japan.
12. C. toli.—The subject of a very extensive fishery on the coast of Sumatra for the sake of its roes, which are salted and exported to China, the dried fish themselves being sent into the interior of the island. The fish is called “Trubu” by the Malays, about 18 inches long, and it is said that between fourteen and fifteen millions are caught annually.
13. C. scombrina.—The “Oil-Sardine” of the eastern coast of the Indian Peninsula.
Other, but less important genera of Clupeoids with serrated abdomen, are Clupeoides, Pellonula, Clupeichthys, Pellona, Pristigaster, and Chirocentrodon (these three last with very small or without any ventral fins).
Albula.—Body oblong, moderately compressed; abdomen flat. Scales of moderate size, adherent; lateral line distinct. Eyes covered with a broad annular adipose membrane. Snout pointed, the upper jaw projecting beyond the lower. Mouth inferior, of moderate width, with villiform teeth; intermaxillary juxtaposed to the upper anterior edge of the maxillary. Dorsal fin opposite to the ventrals; anal fin shorter than dorsal. Gill-membranes entirely separate, with numerous branchiostegals.
One species only (A. conorhynchus), ranging over all tropical and sub-tropical seas, and very common in many localities near the coasts. It grows to a length of from two to three feet, and is not valued as food.
Elops.—Body rather elongate, moderately compressed; abdomen flat. Scales small, adherent; lateral line distinct. A narrow osseous lamella, attached to the mandibulary symphysis, covers the part between the mandibles. Snout pointed; mouth wide, anterior; intermaxillary short, maxillary forming the lateral part of the mouth. Bands of villiform teeth in the jaws, on the vomer, palatine and pterygoid bones, on the tongue, and on the base of the skull. Dorsal fin opposite to ventrals; anal rather shorter than dorsal. Gill-membranes entirely separate, with very numerous branchiostegals.
Two species, of which one, E. saurus, is, like the preceding fish, spread over all tropical and sub-tropical seas; it exceeds a length of three feet, and is not esteemed as food.
Fig. 301.—Elops saurus.
Megalops.—Body oblong, compressed, abdomen flat. Scales large, adherent; lateral line distinct. A narrow osseous lamella, attached to the mandibulary symphysis, between the mandibles. Snout obtusely conical; mouth anterior, lower jaw prominent; intermaxillary short; maxillary forming the lateral part of the mouth. Bands of villiform teeth in the jaws, on the vomer, palatine and pterygoid bones, on the tongue and on the base of the skull. Dorsal fin opposite to, or immediately behind, the ventrals; anal rather larger than dorsal. Gill-membranes entirely separate, with numerous branchiostegals. Pseudobranchiæ none.
Two species, one belonging to the Indo-Pacific (M. cyprinoides), the other to the Atlantic (M. thrissoides); they are the largest fishes of this family, exceeding a length of five feet, and excellent eating. Young specimens enter freely fresh waters.
Chanos.—Body oblong, compressed; abdomen flat. Scales small, striated, adherent; lateral line distinct. Snout depressed; mouth small, anterior, transverse, the lower jaw with a small symphysial tubercle. Intermaxillary in juxtaposition to the upper anterior edge of maxillary. Teeth none. Dorsal fin opposite to the ventrals; anal small, shorter than dorsal; caudal deeply forked. Gill-membranes entirely united below, and free from the isthmus. Branchiostegals four, long. An accessory branchial organ in a cavity behind the gill-cavity proper. Air-bladder divided by a constriction into an anterior and posterior portion. Mucous membrane of the œsophagus raised in a spiral fold. Intestine with many convolutions.
Two species from the Indo-Pacific, of which Ch. salmoneus is extremely common; it enters fresh waters, and exceeds a length of four feet; its flesh is highly esteemed. The accessory branchial organ and the skeleton have been described by Müller, “Bau und Grenzen der Ganoiden,” p. 75; and by Hyrtl, “Denkschr. Ak. Wiss. Wien.” xxi. 1883, p. 1.
Fig. 302.—Chanos salmoneus.
The remaining genera belonging to this family are Spratelloides, Dussumieria, and Etrumeus, which together form a small group, distinguished by an anterior and lateral mouth, by the upper jaw not overlapping the lower, by a rounded abdomen, and by lacking the gular plate of some of the preceding genera.
Body oblong, with rounded abdomen, covered with cycloid scales; head naked; barbels none. Margin of the upper jaw formed by the intermaxillaries mesially, and by the maxillaries laterally. Opercular apparatus complete. Adipose fin none; dorsal fin much elongate, many rayed; anal fin short. Stomach with a blind sac; pyloric appendages numerous. Gill-apparatus well developed; pseudobranchiæ; gill-openings wide; an air-bladder. Ova very small; ovaries without duct.
One genus and species only (Bathythrissa dorsalis) from deep water (350 fathoms) off the coast of Japan. This remarkable fish has the appearance of a Coregonus, and attains to a length of two feet. Nothing is known of its osteology, but possibly a fossil genus from the Gyps of Montmartre; Notæus, which has also a long dorsal fin, may prove to belong to the same family.
Body covered with thin, deciduous scales; barbels none. Margin of the upper jaw formed by the intermaxillaries mesially, and by the maxillaries laterally, both bones being firmly united, in juxtaposition. Opercular apparatus complete. Adipose fin none; the dorsal fin belongs to the caudal portion of the vertebral column. Stomach with a blind sac; intestine short, the mucous membrane forming a spiral fold; pyloric appendages none. Pseudobranchiæ none; air-bladder incompletely divided into cells; gill-opening wide.
One genus and species only (Chirocentrus dorab) is known, which is common in the Indian Ocean, and attains to a length of about three feet; it is not esteemed as food. Remains of fishes similar to Chirocentrus are found in the marl slates of Padang, in Sumatra.
Body with or without scales; head naked; barbels none. Margin of the upper jaw formed by the intermaxillaries and maxillaries, the former being placed along the upper anterior edge of the latter. Opercular apparatus complete. Adipose fin none; the dorsal fin belongs to the caudal portion of the vertebral column. Stomach curved, without blind sac; pyloric appendages in moderate number. Pseudobranchiæ; air-bladder absent. Gill-openings very wide.
Before the voyage of the “Challenger” one species only of this family was known, Alepocephalus rostratus, a rare fish from the Mediterranean; now, four genera with seven species are known, and there is no doubt that this family is one of the most characteristic, and will prove to be one of the most generally distributed forms, of the deep-sea. Their vertical range varies between 345 (Xenodermichthys) and 2150 (Bathytroctes) fathoms. They approach the Salmonoids, but lack invariably the adipose fin. Their dentition is very feeble; their eye large; bones thin. Coloration black.
Alepocephalus has thin cycloid scales; a mouth of moderate width, and no teeth on the maxillary.
Bathytroctes has cycloid scales, a wide mouth, and teeth on the maxillary as well as intermaxillary.
Platytroctes has small keeled scales and no ventrals.
Xenodermichthys with fine nodules instead of scales.
Head and body scaly; barbels none. Margin of the upper jaw formed by the intermaxillaries mesially, and by the maxillaries laterally. Opercular apparatus incomplete. Tail prolonged, tapering. Adipose fin none. Dorsal short, belonging to the caudal portion of the vertebral column; anal very long. Stomach without blind sac; two pyloric appendages. Pseudobranchiae none; air-bladder present, divided in the interior. The ova fall into the cavity of the abdomen before exclusion. On each side a parieto-mastoid cavity leading into the interior of the skull.
One genus only (Notopterus) with five species which inhabit fresh waters of the East Indies and West Africa. Well-preserved remains of this genus occur in the marl slates of Padang, in Sumatra. Their air-bladder is divided into several compartments, and terminates in two horns anteriorly and posteriorly, the anterior horns being in direct connection with the auditory organ.
Body covered with cycloid scales; head scaly; barbels none. Margin of the upper jaw formed by the intermaxillaries mesially, and by the maxillaries laterally. Opercular apparatus incomplete. Adipose fin none. The short dorsal belongs to the abdominal part of the vertebral column; anal very long. Stomach with a blind sac; intestine short; pyloric appendages in moderate number. Pseudobranchiæ none. Air-bladder large, simple; gill-openings wide. Ovaries closed.
The only genus belonging to this family was discovered by the Madeiran ichthyologist Johnson, in 1863; but since then the naturalists of the “Challenger” expedition have added four other species, showing that this type is a deep-sea form and widely distributed; the specimens were dredged in depths varying from 560 to 2750 fathoms.
Body generally with four series of subtriangular scutes, and with intermediate scale-like smaller ones. One (?) dorsal only; head long, with the jaws produced.
Extinct; developed in the chalk and extending into tertiary formations: Dercetis (with the upper jaw longest), Leptotrachelus, Pelargorhynchus, Plinthophorus, Saurorhamphus (with the lower jaw longest), Eurypholis; Ischyrocephalus (?). The latter genus, from cretaceous formations of Westphalia, is said to have two dorsal fins.
Head scaleless; barbels none. Body elongate, eel-shaped. Margin of the upper jaw formed in the middle by the intermaxillaries, and laterally by the maxillaries. Dorsal fin absent or reduced to an adipose strip; caudal generally absent, the tail terminating in a point. Anal fin exceedingly long. Ventrals none. Extremity of the tapering tail capable of being reproduced. Vent situated at, or at a short distance behind, the throat. Humeral arch attached to the skull. Ribs well developed. Gill-openings rather narrow. Air-bladder present, double. Stomach with a cæcal sac and pyloric appendages. Ovaries with oviducts.
Eel-like freshwater fishes from Tropical America.
Sternarchus.—Tail terminating in a distinct small caudal fin. Teeth small. A rudimentary dorsal fin is indicated by an adipose band fitting into a groove on the back of the tail; it is easily detached, so as to appear as a thong-like appendage fixed in front. Branchiostegals four.
Eight species, some have the snout compressed and of moderate length, like St. Bonapartii from the River Amazons; others have it produced into a long tube, as St. oxyrhynchus from the Essequibo.
Rhamphichthys.—Caudal fin none; teeth none; no trace of a dorsal fin. No free orbital margin.
Six species, of which, again, some have a tubiform snout, whilst in the others it is short.
Sternopygus.—Caudal fin none; no trace of a dorsal fin. Both jaws with small villiform teeth; similar teeth on each side of the palate. Body scaly.
Four species, very common, and growing to a length of 30 inches.
Carapus.—Caudal fin none; no trace of a dorsal fin. A series of conical teeth in each jaw. Anterior nostrils, wide in the upper lip. Body scaly.
One species (C. fasciatus) extremely common, and found all over tropical America, east of the Andes, from 18 to 24 inches long.
Gymnotus.—Caudal and dorsal fins absent; anal extending to the end of the tail. Scales none. Teeth conical, in a single series. Eyes exceedingly small.
The “Electric Eel” is the most powerful of electric fishes, growing to a length of six feet, and extremely abundant in certain localities of Brazil and the Guyanas. The electric organ consists of two pairs of longitudinal bodies, situated immediately below the skin, above the muscles; one pair on the back of the tail, and the other pair along the anal fin. Each fasciculus is composed of flat partitions or septa, with transverse divisions between them. The outer edge of the septa appear in nearly parallel lines in the direction of the longitudinal axis of the body, and consist of thin membranes, which are easily torn; they serve the same purpose as the columns in the analogous organ of the Torpedo, making the walls or abutments for the perpendicular and transverse dissepiments, which are exceedingly numerous, and so closely aggregated as to seem almost in contact. The minute prismatic cells, intercepted between these two sorts of plates, contain a gelatinous matter; the septa are about one-thirtieth of an inch from each other, and one inch in length contains a series of 240 cells, giving an enormous surface to the electric organs. The whole apparatus is supplied with more than 200 nerves, which are the continuations of the rami anteriores of the spinal nerves. In their course they give out branches to the muscles of the back, and to the skin of the animal. In the Gymnotus, as in the Torpedo, the nerves supplying the electric organs are much larger than those bestowed on any part for the purposes of sensation or movement.
The graphic description by Humboldt of the capture of Electric Eels by horses driven into the water, which would receive the electric discharges and thus exhaust the fishes, seems to rest either on the imagination of some person who told it to the great traveller or on some isolated incident. Recent travellers have not been able to verify it even in the same parts of the country where the practice was said to exist.
Body elongate, naked or covered with minute scales; barbels none. Margin of the upper jaw formed by the intermaxillaries only, the well developed maxillaries lying behind and parallel to them. Paired fins none. Vertical fins rudimentary, reduced to more or less distinct cutaneous folds. Vent situated at a, great distance behind the head. Ribs present. Gill-openings confluent into one slit situated on the ventral surface. Air-bladder none. Stomach without cæcal sac or pyloric appendages. Ovaries with oviducts.
The fishes of this family consist of freshwater-fishes from tropical America and Asia, which, however, enter also brackish water; and of a truly marine genus from Australia.
Amphipnous.—Vent in the posterior half of the body, which is covered with minute scales longitudinally arranged.
A common fish (A. cuchia) in Bengal, remarkable for its singular respiratory apparatus. It has only three branchial arches, with rudimentary branchial laminæ, and with very narrow slits between the arches. To supplement this insufficient respiratory apparatus, a lung-like sac is developed on each side of the body behind the head, opening between the hyoid and first branchial arch. The interior of the sac is abundantly provided with blood-vessels, the arterial coming from the branchial arteries, whilst those issuing from it unite to form the aorta. A. cuchia approaches the Eels in having the humeral arch not attached to the skull.
Monopterus.—Vent in the posterior half of the body, which is naked. Three branchial arches with rudimentary gills, but without breathing sac.
One species (M. javanicus), which is extremely common in the East Indian Archipelago and in the eastern parts of the Continent. Upwards of three feet long.
Symbranchus.—Vent in the posterior half of the body, which is naked. Four branchial arches with well developed gills.
Three species, of which one (S. marmoratus) is extremely common in tropical America, and the other (S. bengalensis) not less so in the East Indies.
Chilobranchus.—Vent in the anterior half of the length of the body, which is naked. Vertical fins reduced to a simple cutaneous fold, without rays.
A small fish (Ch. dorsalis) from North Western Australia and Tasmania.
Body elongate, cylindrical or “band-shaped, naked or with rudimentary scales. Vent situated at a great distance from the head. Ventral fins none. Vertical fins, if present, confluent, or separated by the projecting tip of the tail. Sides of the upper jaw formed by the tooth-bearing maxillaries, the fore part by the intermaxillary, which is more or less coalescent with the vomer and ethmoid. Humeral arch not attached to the skull. Stomach with a blind sac; no pyloric appendages. Organs of reproduction without efferent ducts.
The “Eels” are spread over almost all fresh waters and seas of the temperate and tropical zones; some descend to the greatest depths of the oceans. The young of some have a limited pelagic existence. (Leptocephali, see p. 179.) At Monte Bolca fossil remains are very numerous, belonging to recent genera, Anguilla, Sphagebranchus, and Ophichthys; even larval Leptocephales have been preserved. Anguilla has been found also in the chalk of Aix and Oeningen.
In the majority of the species the branchial openings in the pharynx are wide slits (Murænidæ platyschistæ); in others, the true Murænæ, (Murænidæ engyschistæ) they are narrow.
Nemichthys.—Exceedingly elongate, band-shaped; tail tapering into a point. Vent approximate to the pectorals, but the abdominal cavity extending far behind the vent. Jaws produced into a long slender bill, the upper part being formed by the vomer and intermaxillaries. The inner surface of the bill covered with small tooth-like asperities. Eye large. The nostrils of each side are close together, in a hollow before the eye. Gill-openings wide, nearly confluent. Pectoral and vertical fins well developed.
This very singular type is a deep-sea form, occurring at depths of from 500 to 2500 fathoms. The two species known have hitherto been found in the Atlantic only.
Cyema.—This genus combines the form of the snout of Nemichthys, with the soft and shorter body of a Leptocephalus; but the gill-openings are very narrow and close together on the abdominal surface. Vent in about the middle of the length of the body; vertical fins well developed, confined to, and surrounding, the tail. Pectoral fins well developed. Eye very small.
Known from two specimens only, 4½ inches long, dredged in depths of 1500 and 1800 fathoms in the Pacific and Antarctic Oceans.
Saccopharynx.—Deep-sea Congers, with the muscular system very feebly developed, with the bones very thin, soft, and wanting in inorganic matter. Head and gape enormous. Snout very short, pointed, flexible, like an appendage overlapping the gape. Maxillary and mandibulary bones very thin, slender, arched, armed with one or two series of long, slender, curved, widely set teeth, their points being directed inwards; palate toothless. Gill-openings wide, at some distance from the head, at the lower part of the sides; gills very narrow, free, and exposed. Trunk of moderate length. Stomach distensible in an extraordinary degree. Vent at the end of the trunk. Tail band-like, exceedingly long, tapering in a very fine filament. Pectoral small, present. Dorsal and anal fins rudimentary.
This is another extraordinary form of Deep-sea Eels; the muscular system, except on the head, is very feebly developed; the bones are as thin, soft, and wanting in inorganic matter, as in the Trachypteridæ. This fish is known from three specimens only, which have been found floating on the surface of the North Atlantic, with their stomachs much distended, having swallowed some other fish, the weight of which many times exceeded that of their destroyer. It attains to the length of several feet.
Synaphobranchus.—Gill-openings ventral, united into a longitudinal slit between the pectoral fins, separate internally. Pectoral and vertical fins well developed. Nostrils lateral, the anterior subtubular, the posterior round, before the lower half of the eye. Cleft of the mouth very wide; teeth small; body scaly. Stomach very distensible.
Deep-sea Congers, with well-developed muscular system, spread over all oceans, and occurring in depths of from 345 to 2000 fathoms. Four species are known. Probably attaining to the same length as the Conger.
Anguilla.—Small scales imbedded in the skin. Upper jaw not projecting beyond the lower. Teeth small, forming bands. Gill-openings narrow, at the base of the pectoral fins. The dorsal fin commences at a considerable distance from the occiput.
Some twenty-five species of “Eels” are known from the freshwaters and coasts of the temperate and tropical zones; none have been found in South America or the west coast of North America and West Africa. The following are the most noteworthy:—The common European species (A. anguilla) is spread over Europe to 64° 30´ lat. N., and all round the Mediterranean area, but is not found either in the Danube or in the Black and Caspian Seas; it extends across the Atlantic to North America. The form of the snout varies much, and some naturalists have believed that specimens with a broad and obtuse snout were specifically distinct from those with pointed snout. However, every degree of breadth of the snout may be observed; and a much safer way of recognizing this species, and distinguishing it from other European Eels, is the forward position of the dorsal fin; the distance between the commencement of the dorsal and anal fins being as long as, or somewhat longer than, the head. Eels grow generally to a length of about three feet, but the capture of much larger examples is on record. Their mode of propagation is still unknown. So much only is certain that they do not spawn in fresh water, that many full-grown individuals, but not all, descend rivers during the winter months, and that some of them at least must spawn in brackish water or in deep water in the sea; for in the course of the summer young individuals from three to five inches long ascend rivers in incredible numbers, overcoming all obstacles, ascending vertical walls or floodgates, entering every larger and smaller tributary, and making their way even over terra firma to waters shut off from all communication with rivers. Such immigrations have been long known by the name of “Eel-fairs.” The majority of the Eels which migrate to the sea appear to return to fresh water, but not in a body, but irregularly, and throughout the warmer part of the year. No naturalist has ever observed these fishes in the act of spawning, or found mature ova; and the organs of reproduction of individuals caught in fresh water are so little developed and so much alike, that the female organ can be distinguished from the male only with the aid of a microscope.
The second species found in Great Britain, on the coasts of Europe generally, in China, New Zealand, and the West Indies, is (A. latirostris) the “Grig” or “Glut,” which prefers the neighbourhood of the sea to distant inland-waters, and in which the dorsal fin begins farther backwards, the distance between the commencement of the dorsal and anal fins being shorter than the head; its snout seems to be always broad. On the American side of the Atlantic other species, beside A. anguilla are found in abundance: A. bostoniensis, A. texana. The largest Eels occur in lakes of the islands of the Indo-Pacific, and they play a conspicuous part in the mythology of the South-Sea Islanders and Maories; individuals of from eight to ten feet in length have been seen, and referred to several species, as A. mauritiana, fidjiensis, obscura, aneitensis, etc.
Conger.—Scaleless. Cleft of the mouth wide, extending at least to below the middle of the eye. Maxillary and mandibulary teeth arranged in series, one of which contains teeth of equal size, and so closely set as to form a cutting edge. No canine teeth. Vomerine band of teeth short. Pectoral and vertical fins well developed, the dorsal commencing behind the root of the pectoral. Gill-openings large, approximate to the abdomen. The posterior nostril opposite to the upper or middle part of the orbit, the anterior in a tube. Eyes well developed.
The “Congers” are marine Eels; the best known species (C. conger) seems to be almost cosmopolitan, and is plentiful all round Europe, at St. Helena, in Japan, and Tasmania. It attains to a length of eight feet, and thrives and grows rapidly even in confinement, which is not the case with the freshwater Eel. Three other species are known, of which C. marginatus from the Indian Ocean, is the most common. Leptocephalus morrisii is an abnormal larval condition of the Conger.
Genera allied to Conger are Poeciloconger, Congromurcæna, Uroconger, and Heteroconger.
Murænesox.—Scaleless. Snout produced. Jaws with several series of small closely set teeth, anteriorly with canines; vomer with several long series of teeth, the middle of which is formed by large conical or compressed teeth. Gill-openings wide, approximate to the abdomen. Pectoral and vertical fins well developed, the dorsal beginning above the gill-opening. Two pairs of nostrils, the posterior opposite to the upper part or middle of the eye.
Four species from tropical seas, M. cinereus being very common in the Indian Ocean, and attaining to a length of six feet.
Nettastoma.—Scaleless. Snout much produced, depressed. Jaws and vomer with bands of card-like teeth, those along the median line of the vomer being somewhat the larger. Vertical fins well developed; pectorals none. Gill-openings of moderate width, open. Nostrils on the upper surface of the head, valvular; the anterior near to the end of the snout, the posterior above the anterior angle of the eye.
This genus lives at some depth, the Japanese species (N. parviceps) having been obtained at 345 fathoms. N. melanurum from the Mediterranean, seems to inhabit a similar depth. Hyoprorus is its Leptocephalid form.
Genera allied to Murcænesox are Saurenchelys, Oxyconger, Hoplunnis, and Neoconger; in all these the nostrils have a superior or lateral position. In other genera the nostrils perforate the upper lip, as in Myrus, Myrophis, Paramyrus, Chilorhinus, Murænichthys, and Ophichthys, the last genus deserving of particular mention on account of its great range and common occurrence.