ZOOLOGICAL
48
LAMNIDA¡ (The Porbeagle, &c.). Plate 26, Map iv.
About seven species are usually referred to this family, belonging to five or six different genera. They are widely distributed, occurring in nearly all seas. The best-known species is the Common Porbeagle (Lamna cornubica), a fierce animal inhabiting the Northern Atlantic and Pacific Oceans, and common in British waters. Another species, Carcharodon rondeletii, is regarded as the most formidable and voracious of all sharks, attaining a length of 40 feet, and found in all tropical and subtropical seas, ranging from the Mediterranean to New Zealand. The curious, long-tailed Pox Shark or Thresher {Alopecias vulpes) is not uncommon on British coasts.
SPHYRNIDA: (Hammer-Head Sharks), Plate 26, Map iv.
A single genus (Sphyrna, formerly called Zygsena) of this family is recognised, with five species. They are widely distributed in all the warmer seas, while one species (Sphyrna zygsena), is occasionally taken off the British coasts. These sharks are remarkable for the curious lateral extensions of the head, which bear an eye at each extremity, and give these fishes an extraordinary hammer-like appearance, whence their popular name.
CARCHARIIDA! (The Blue Shark, &c.). Plate 26, Map v.
This family is a comparatively large one, comprising about 60 species These have a world-wide distribution, ranging from Iceland to New Zealand, and occurring in all seas. Numerous genera have ,been formed for the reception of the various forms, the typical one {Carcharían) containing about half of them. The best-known members of this important family are the so-called Blue Shark {Carcharías glaucus), the Topes of the genus Galeus, and the “ Hounds ” or species of Mustelus. The Blue Shark is frequently captured in British waters; Galeus canis, the Common Tope, is also common off our coasts; while Mustelus vulgaris and M. Isevis are both well-known inhabitants of British seas.
SCYLLIIDAI (Dog-Fishes, &c.). Plate 26, Map v.
About 20 species of Dog-Fishes constitute the present family, and these are found in the seas of the whole world. The members of the typical genus Scyllium are of small size, and are sometimes used as food. Two species, called respectively the Small-spotted and Large-spotted Dog-Fish (<S׳. canícula and catulus) are common off the British coasts j while Pristiurus melanostomus, known as the Black-mouthed Dog-Fish, is a European species which has several times been captured in British waters. The Tiger- or Zebra-Shark {Stegostoma tigrinum) is a common inhabitant of the Indian Ocean, owing its popular name to the handsome coloration of its body, which is of a brownish-yellow, striped with dark brown or black.
HETERODONTIDA3 (Bullhead Sharks). Plate 26, Map v.
The species of this family, four in number, are confined to the Pacific Ocean, where, however, they have a wide range. The best-known species is that called popularly the Port Jackson Shark {Heterodon philippi), a somewhat repulsive-looking creature inhabiting the seas of Australia. Little is known of the habits of these Sharks, but they appear to feed chiefly on Molluscs. None of them exceeds five feet in length.
NOTIDANIDA! (Comb-toothed Sharks). Plate 26, Map v.
This family comprises about half a dozen species of moderate-sized Sharks, which are found in nearly all tropical and temperate seas. Notidanus griseus, inhabiting the Atlantic and the Mediterranean, is an occasional visitant to British waters.
CYCLOSTOMATA.
PETROMYZONTIDJE (Lampreys). Plate 26, Map vi.
The lowly-organised fishes known as Lampreys are found on the coasts and in the fresh waters of a great part of the globe, but most of the records, perhaps naturally enough, have been made in the Northern Hemisphere. Three species are recorded as British, namely, the Sea-Lamprey {Petrcmyzon marinus), not uncommon off our coasts ; the Lampern or Rivdr-Lamprey {P. Jluviatilis), generally distributed in rivers, and the Pride, Sandpiper, or Small Lamprey (P. branchialis), found throughout the rivers and streams of the British Isles. Geotria is a southern genus, occurring in the rivers of Chili, South Australia and New Zealand; while Mordacia has an equally interesting distribution, being confined, so far as at present known, to the coasts of Chili and Tasmania.
BDELLOSTOMATIDA: (Hag-Fishes). Plate 26, Map vi.
The members of this family are confined to the coasts of the Pacific, being recorded principally from California, Chili, Patagonia, Japan and New Zealand; and the South Atlantic, where they occur at the Cape of Good Hope. In general appearance and habits they resemble the Hag-Fishes of the next family, differing in structure principally in possessing six to fourteen pairs of gill-openings, whereas in the Myxinid* the six pairs of gill-sacs open to the exterior by a common orifice on each side.
MYXINIDA! (Hag-Fishes). Plate 26, Map vi.
The principal character which distinguishes these Hag-Fishes from the Bdellostomatidse has been pointed out in the preceding paragraph. A single genus {Myxine) is here included, with at least half a dozen species. They are widely distributed, but chiefly in temperate seas, and one species, the so-called Glutinous Hag or Borer (M. glutinosa), is abundant on the British coasts. It is eel-like in appearance, and enters the bodies of other fishes, especially cod fishes, to feed upon their flesh.
ORDER PLAGIOSTOMI.
MYLIOBATIDA¡ (Eagle-Rays). Plate 26, Map i.
The Eagle Bays are represented by about 30 species, which occur principally in tropical and subtropical seas. The best-known species is Myliobatis aquila, which has been taken on many parts of the British coasts, while beyond our seas it has an almost cosmopolitan distribution.
TRYGONIDA¡ (Sting-Rays). Plate 26, Map i.
The Sting-Rays owe their popular name to the strong caudal spines, with which they are capable of inflicting severe and dangerous wounds. About 50 species are known, which have a wide range in tropical and temperate seas. A single species, Trygon pastinaca, occurs not infrequently in British waters, while it ranges also over both sides of the Atlantic, the Mediterranean, and even as far east as China and Japan. A few species live in fresh waters, and these are mainly found in the northern portion of South America.
TORPEDINIDA! (Electric Rays). Plate 26, Map ii.
The Electric Rays, so called from the presence of electric organs between the head and the pectoral fins, are found chiefly in warm seas, although one species {Torpedo hebetans) has frequently been taken off the British coasts. Seven genera and about 15 species have been described.
RAIIDAI (Rays or Skates). Plate 26, Map ii.
The species of this family, some 30 or 40 in number, are found in all the cooler waters of the globe, and are more abundant in the Northern than in the Southern Hemisphere. The great majority of the species belong to the typical genus Raia, as do all the British representatives of the family. The latter are nine in number, the best-known of which are the Common Skate (R. batis) and the Thornback Ray {R. clavata). Most of the Rays are eaten as food.
RHINOBATIDA¡ (Beaked Rays). Plate 26, Map ii.
The Rhinobatidse inhabit warmer regions than the True Rays (Raiidse), and are found in nearly all tropical and subtropical seas. About 20 species have been described, belonging to five different genera. The peculiar shape of the body in these Rays has led to their being sometimes called guitar-fishes or fiddler-fishes.
PRISTIDA3 (True Saw-Fishes). Plate 26, Map iii.
This is a small group, containing only a single genus and four or five species. They are formidable fishes, attaining a length of over 20 feet, and are found in all the warmer seas. Carnivorous in habit, these creatures, with their serrated beak, cause much havoc among their defenceless neighbours. ־*$
PRISTIOPHORIDAJ (Side-gilled Saw-Fishes). Plate 26, Map iii.
As their popular name indicates, these fishes may be distinguished from the true Saw-Fishes forming the previous family by the position of their gill-openings, which are lateral instead of ventral. In general appearance, however, they resemble the Pristidse. About four species, belonging to a single genus, Pristiophorus, are known, and these are confined to the seas of Australia and Japan.
RHINIDA1 (Angel-Fishes). Plate 26, Map iii.
The members of this family are all very closely allied to one another, and it is doubtful whether more than a single species should be recognised. Angel-Fishes have an almost cosmopolitan distribution, occurring in practically all the tropical and temperate seas. They attain a length of about five feet. Rhina squatina, the typical species, is not uncommon in British waters, especially off the Scottish coasts.
SPINACIDA3 (Spiny Dog-Fishes). Plate 26, Map iii.
About 20 species of this family are known, belonging to eight genera. They have a world-wide distribution, but are most abundant in temperate seas. The best-known member of the group is the Picked or Piked Dog-Fish {Acanthias vulgaris), a creature growing to a length of three or four feet, and abundant on the British coasts. The Greenland Shark {Lsemargus borealis) is an occasional visitor to British seas, but inhabits principally the Arctic regions. The Spinous Shark {Echinorhinus spinosus) is another well-known member of the family, wandering on rare occasions to Britain.
RHINODONTIDA! (Whale-Sharks). Plate 26, Map iv.
The Rhinodontidse have a wide distribution, but are only rarely seen. One, or perhaps two, species may be recognised, belonging to a single genus Rhinodon. These creatures are the largest known Sharks, growing to a length of over 50 feet. Little is recorded of their habits, but the size of their teeth suggests that their food consists of small fishes. They are, at any rate, reported to be quite harmless to man.
CETORHINIDA¡ (The Basking Shark). Plate 26, Map iv.
The Basking Shark {Cetorhinus maximus) is the sole representative of this family. It inhabits Arctic seas, but wanders as far south as the Mediterranean and California. It is a huge creature, attaining a length of 40 feet, but is harmless to man, by whom it is regularly hunted for the sake of the oil obtained from its liver. The popular name of this Shark, which occurs fairly commonly in British seas, is due to its habit of lying motionless on the surface of the water.