CHAPTER XXI.

THE FISHES OF THE DEEP SEA 296

Deep-sea fishes a recent discovery, 296--Physical conditions affecting these fishes, 297--Characteristics of Deep-sea fishes, 299--Their vertical and horizontal distribution, 304--List of Deep-sea fishes, 305.

SYSTEMATIC AND DESCRIPTIVE PART.

FIRST SUB-CLASS--PALÆICHTHYES.

PAGE FIRST ORDER--CHONDROPTERYGII 313

I. _Plagiostomata_ 313

A. _Selachoidei--Sharks_ 314

Families: Carchariidæ (Blue Shark, Tope, Hammerhead, Hound), 316--Lamnidæ (Porbeagle, Carcharodon, Fox-Shark, Basking-Shark), 319--Rhinodontidæ, 323--Notidanidæ, 324--Scylliidæ (Dog-fishes), 325--Hybodontidæ, 328--Cestraciontidæ (Port Jackson Shark), 328--Spinacidæ (Spiny Dogs, Greenland Shark), 330--Rhinidæ, 334--Pristiophoridæ, 335.

B. _Batoidei--Rays_ 335

Families: Pristidæ (Saw-fishes), 336--Rhinobatidæ, 337--Torpedinidæ (Electric Rays), 338--Rajidæ (Rays and Skates), 340--Trygonidæ (Sting Rays), 342--Myliobatidæ (Eagle Rays), 344.

II. _Holocephala_ 348

Family: Chimæridæ, 348.

SECOND ORDER--GANOIDEI 350

I. _Placodermi_ 351

II. _Acanthodini_ 355

III. _Dipnoi_ 355

Families: Sirenidæ (Lepidosiren, Protopterus, Ceratodus), 355--Ctenododipteridæ, 359--Phaneropleuridæ, 360.

IV. _Chondrostei_ 360

Families: Acipenseridæ (Sturgeons), 360--Polyodontidæ, 362.

V. _Polypteroidei_ 363

Families: Polypteridæ, 364--Saurodipteridæ, 365--Coelacanthidæ, 365--Holoptychidæ, 365.

VI. _Pycnodontoidei_ 366

Families: Pleurolepidæ, 366--Pycnodontidæ, 366.

VII. _Lepidosteoidei_ 367

Families: Lepidosteidæ, 367--Sauridæ, 368--Stylodontidæ, 368--Sphærodontidæ, 368--Aspidorhynchidæ, 369--Palæoniscidæ, 369--Platysomidæ, 370.

VIII. _Amioidei_ 370

Families: Caturidæ, 371--Leptolepidæ, 371--Amiidæ (Bow-fin), 371.

SECOND SUB-CLASS--TELEOSTEI.

FIRST ORDER--ACANTHOPTERYGII 374

I. _A. perciformes_ 374

Families: Percidæ (Freshwater-Perches, Bass, Sea-Perches, Centrarchus), 375--Squamipinnes (Coral-Fishes), 397--Mullidæ (Red-Mullets), 403--Sparidæ (Sea-breams), 405--Hoplognathidæ, 410--Cirrhitidæ, 410--Scorpænidæ, 412--Nandidæ, 418--Polycentridæ, 418--Teuthididæ, 418.

II. _A. beryciformes_ 419

Family: Berycidæ, 420.

III. _A. kurtiformes_ 424

Family: Kurtidæ, 424.

IV. _A. polynemiformes_ 425

Family: Polynemidæ, 425.

V. _A. sciæniformes_ 426

Family: Sciænidæ (Meagres), 426.

VI. _A. xiphiiformes_ 431

Family: Xiphiidæ (Sword-fishes), 431.

VII. _A. trichiuriformes_ 433

Families: Trichiuridæ (Scabbard-fishes, Hairtails), 433--Palæorhynchidæ, 437.

VIII. _A. cotto-scombriformes_ 438

Families: Acronuridæ (Surgeons), 438--Carangidæ (Horse-Mackerels, Pilot-fish, Boar-fish), 440--Cyttidæ (John Dorey), 450--Stromateidæ, 452--Coryphænidæ (Dolphin, Sun-fish), 452--Nomeidæ, 455--Scombridæ (Mackerel, Tunny, Bonito, Albacore, Sucking-fish), 456--Trachinidæ (Stare-gazer, Weever, etc.), 462--Malacanthidæ, 467--Batrachidæ, 467--Psychrolutidæ, 469--Pediculati (Angler, Antennarius, etc.), 469--Cottidæ (Bull-heads, Gurnards), 476--Cataphracti (Flying Gurnards), 480--Pegasidæ, 482.

IX. _A. gobiiformes_ 483

Families: Discoboli (Lump-suckers), 483--Gobiidæ (Gobies, Dragonets), 485.

X. _A. blenniiformes_ 490

Families: Cepolidæ (Band-fishes), 490--Trichonotidæ, 490--Heterolepidotidæ, 491--Blenniidæ (Wolf-fish, Blennies), 492--Acanthoclinidæ, 498--Mastacembelidæ, 499.

XI. _A. mugiliformes_ 499

Families: Sphyrænidæ (Barracudas), 499--Atherinidæ (Atherines), 500--Mugilidæ (Mullets), 501.

XII. _A. gastrosteiformes_ 504

Families: Gastrosteidæ (Sticklebacks), 504--Fistulariidæ (Flute-mouths), 507.

XIII. _A. centrisciformes_ 508

Family: Centriscidæ, 508.

XIV. _A. gobiesociformes_ 510

Family: Gobiesocidæ, 512.

XV. _A. channiformes_ 513

Family: Ophiocephalidæ, 513.

XVI. _A. labyrinthibranchii_ 514

Families: Labyrinthici (Climbing Perch, Gourami), 514--Luciocephalidæ, 519.

XVII. _A. lophotiformes_ 519

Family: Lophotidæ, 519.

XVIII. _A. tæniiformes_ 520

Family: Trachypteridæ (Ribbon-fishes), 520.

XIX. _A. notacanthiformes_ 523

Family: Notacanthidæ, 523.

SECOND ORDER--ACANTHOPTERYGII PHARYNGOGNATHI 523

Families: Pomacentridæ (Coral-fishes), 524--Labridæ (Wrasses, Parrot-wrasses), 525--Embiotocidæ, 533--Chromides, 534.

THIRD ORDER--ANACANTHINI 537

I. _A. gadoidei_ 537

Families: Lycodidæ, 537--Gadidæ (Cod-fishes, Hake, Burbot, Ling, Rockling, Torsk), 539--Ophidiidæ (Brotula, Fierasfer, Sand-eel, Congrogadus), 546--Macruridæ, 551.

II. _A. pleuronectoidei_ 553

Family: Pleuronectidæ (Flat-fishes), 553.

FOURTH ORDER--PHYSOSTOMI 559

Families: _Siluridæ_; their skeleton, 559--divided into eight subdivisions and sixteen groups; Clariina, 563--Plotosina, 563--Silurina, 565--Hypophthalmina, 566--Bagrina, 567--Amiurina, 567--Pimelodina, 568--Ariina, 569--Doradina, 572--Rhinoglanina, 573--Malapterurina (Electric Catfish), 574--Hypostomatina (Preñadillas, Loricaria, etc.), 575--Aspredinina, 580--Nematogenyina and Trichomycterina, 581--Stegopholina, 581.

Families of Physostomi continued: Scopelidæ, 582--_Cyprinidæ_ (Carps), 587--divided into fourteen groups, viz. Catostomina (Suckers), 588--Cyprinina (Carp, Crucian Carp, Gold-fish, Barbels, Gudgeons), 589--Rohteichthyina, 596--Leptobarbina, 597--Rasborina, 597--Semiplotina, 598--Xenocypridina, 598--Leuciscina (White fish, Tench, Dace, etc.), 598--Rhodeina, 601--Danionina, 601--Hypophthalmichthyina, 602--Abramidina (Bream, Bleak), 602--Homalopterina, 604--Cobitidina (Loaches), 604.

Families of Physostomi continued: Kneriidæ, 606--Characinidæ, 606--Cyprinodontidæ, 613--Heteropygii (Blind Fish of the Mammoth Cave), 618--Umbridæ, 619--Scombresocidæ (Gar-pike, Saury, Half-beak, Flying Fish), 619--Esocidæ (Pike), 623--Galaxiidæ, 624--Mormyridæ, 625--Sternoptychidæ, 627--Stomiatidæ, 629.

Families of Physostomi continued--_Salmonidæ_: Salmo, difficulty of distinguishing species, 630; constant specific characters, 635--hybrids, 638--sexual development, 638--migratory species and their retention in freshwater, 639--Growth of Salmonoids, 641--their domestication and acclimatisation, 641--species enumerated, 642--Smelt and Capelin, 646--Coregonus, 647--Grayling, 649--marine genera, 650.

Families of Physostomi continued: Percopsidæ, 651--Haplochitonidæ, 651--Gonorhynchidæ, 652--Hyodontidæ (Moon-eye), 653--Pantodontidæ, 653--Osteoglossidæ, 653--Clupeidæ (Herrings, Anchovies, Shads, Mossbanker, Menhaden, etc.), 655--Bathythrissidæ, 663--Chirocentridæ, 663--Alepocephalidæ, 664--Notopteridæ, 664--Halosauridæ, 665--Hoplopleuridæ, 665--Gymnotidæ (Electric Eel), 666--Symbranchidæ, 668--Murænidæ (Eels, Congers, Murænas, etc.), 669.

FIFTH ORDER--LOPHOBRANCHII 678

Families: Solenostomidæ, 678--Syngnathidæ (Pipe-fishes, Sea-horses), 679.

SIXTH ORDER--PLECTOGNATHI 683

Families: Sclerodermi (File-fishes, Coffer-fishes), 684--Gymnodontes (Globe-fishes, Sun-fish), 686.

THIRD SUB-CLASS--CYCLOSTOMATA.

Families: Petromyzontidæ (Lampreys), 691--Myxinidæ, 694.

FOURTH SUB-CLASS--LEPTOCARDII.

Family: Cirrhostomi (Lancelets), 696.

APPENDIX.

DIRECTIONS FOR COLLECTING AND PRESERVING FISHES 697

ALPHABETICAL INDEX 707

INTRODUCTORY REMARKS.

According to the views generally adopted at present, all those Vertebrate animals are referred to the Class of Fishes, which living in water, breathe air dissolved in water by means of gills or branchiæ; whose heart consists of a single ventricle and single atrium; whose limbs, if present, are modified into fins, supplemented by unpaired, median fins; and whose skin is either naked, or covered with scales or osseous plates or bucklers. With few exceptions fishes are oviparous. However, there are not a few members of this Class which show a modification of one or more of these characteristics, as we shall see hereafter, and which, nevertheless, cannot be separated from it. The distinction between the Class of Fishes and that of Batrachians is very slight indeed.

The branch of Zoology which treats of the internal and external structure of fishes, their mode of life, and their distribution in space and time, is termed Ichthyology.[1]