Photo by A. S. Rudland & Sons. Photo by Scholastic Photo. Co.] [Parson's Green.

BONY PIKE.

One of the very few survivors of the ancient group of Enamel-scaled Fishes. 662

Bony Pike, Bow^fin, Sturgeon, ReecUfish, and Bichir 663

probably caused by the escape of air from the air-bladder. During the breeding-season the male takes entire charge of the eggs. The STURGEONS differ from the other fan-fmned fishes in many particulars. To begin with, the skeleton

Photo by A. S. Rudland Jc Sons. is almost entirely cartilagi- STURGEON. nous instead of bony, whilst The air-bladder of the sturgeon is used for making isinglass, its roe for caviare. externally the body is either naked or covered with bony bucklers, arranged symmetrically. The snout is prolonged into a more or less shovel-shaped beak, used for turning over the mud at the bottom of the water in search of prey, and in some forms this becomes further developed into a spoon-shaped paddle, constituting one of the most remarkable appendages of fishes.

Sturgeons grow to a large size, and are the largest of the fresh-water fishes of the

Pkolo by A. S. Rudland & Sons. STERLET. A smaller species of the Sturgeon group. northern hemisphere. The GIANT STURGEON of the Black and Caspian Seas and the Sea of Azoff attains a length of 24 feet, and sometimes more, specimens of 3,200 Ibs. weight having been recorded. On account of the wholesomeness of their flesh, sturgeons are highly esteemed wherever they are found. In Russian rivers they are very abundant, regular fishing-stations being established for their capture. The approach of a shoal of fish is announced by a watchman, and it is said as many as 15,000 sturgeon have been captured at one ofthese stations in a single day. Should the fishing be suspended for a short time, the fish assemble in such numbers as to form a solid mass, completely blocking a river 400 feet in width and 25 feet in depth. From the roe of these Photo by A. s. RudLand & fishes caviare is made, and BICHIR. isiIlglaSS from the inner lining A second representative of the Enamel-scaled group.

of the World664 The Living Animals

of the air-bladder. But the best-flavoured flesh and the finest caviare are obtained from a comparatively small form, the STERLET, a species which does not exceed a yard in length. It is common in the Black and Caspian Seas, the Siberian rivers, and the Danube as far as Vienna. With the Sturgeons we come to the end of Photo ly Scholastic Photo. Co.] [Parson's Green. t ne Fan-finned Fishes. The Fringe-finned group Note the remarkable finlets on the back and the peculiar structure of the breast-fins. are represented to-day only by the BiCHiR and the KEED-FISH. These are extremely interesting forms, if only because they are the sole survivors of a once numerous tribe, the remains of which occur as fossils in some of the oldest geological formations. They are known as Fringe-finned on account of the fact that the rays which support the fin-membrane in the paired fins are ranged round a lobe-shaped base, instead of running directly backwards to the body. As in the bony pike, the body is clothed externally by large quadrangular bony plates of considerable thickness, and coated with a layer of enamel.

The BICHIR, which is found in the Nile and other tropical rivers of Africa, is easily recognised by the peculiar structure of the back-fin, which takes the form of a series of detached isfinlets, varying in number from eight to eighteen. The length attained by the bichir about 4 feet. Gill-breathing is supplemented by the air-bladder, which is used as a respiratory organ, the expired air escaping by a slit, known as the " spiracle." The young bichir breathes, like a tadpole, by means of large external gills, projecting backwards on. each side of the head; later these are replaced by the more efficiently protected internal gills.

The only surviving relative of the bichir is the EEED-FISH of Old Calabar, which differs by its eel-like form and the absence of the hinder paired fins.

CHAPTER, XVI.

SHARKS AND RAYS.

BY F. G. AFLALO, F.Z.S.

prevalent errors with reference to sharks continually recur in England. The is local, and has reference to the absence of " proper " sharks, whatever that mayTWO first mean, from British waters. The second, of wider application, holds that all sharks are dangerous to man. When, some few years ago, the writer addressed a letter to the Times newspaper, warning yachting-men against summer bathing in deep water in Cornwall, a host of critics accused him of a tendency to pose as an alarmist, and insisted that he was confusing sharks with dog-fish. Apart from the fact that the distinction between the two groups is in some cases extremely slight it does not even rely on size, for there are dog-fishes which attain to larger dimensions than the smallest sharks these gentlemen were wholly in error, since four sharks at any rate are very common in Cornish seas, and even occur in lesser numbers on other parts of the British coasts. The largest of these, the great BASKING-

1'koto by W. Saville-Kent, F.Z.S.] iMUford-on-Sea.

WOLLIBONG, OR CARPET-SHAHK.

The leaf-like processes surrounding the head serve to attract prey, while the shark lies concealed on the sea-bottom.

by W. Savilte-Kent, F.Z.S.] [Milford-on-Sea,.

SPOTTED SHARK.

Note the peculiar shape of the tail, and the aperture behind the eye, known as the " spiracle. " S65 84

of the World666 The Living Animals

SHARK (of which a photograph, taken at Mevagissey, is given below), illustrates in its harmless person the fallacy of condemning all sharks as man-eaters, since in this, the largest of its its habit of lying at the surface with therace, we have an absolutely innocuous fish. From large back-fin erect, it is also known as the Sail-fish, while the equally appropriate name of Sun-fish sometimes causes confusion with other British fishes properly so called.

A commoner British shark (in the limited space allotted, British species must be allowed prior claims) is the BLUE SHARK, small examples of which, weighing 30 or 40 Ibs., the writer this fish has a curious andhas often killed with the rod at Mevagissey. When thus hooked, very trying habit of revolving rapidly in the water, scoring its own granulated skin with the line. The PORBEAGLE-SHARK, another Cornish species, is of thicker build than the last, and swims with far less graceful movements. It is a deep brown colour above, and its general

Photo by S. Dalby Smith] [Mevagiiscy. BASKING-SHAKK. Regularly hunted on the west coast of Ireland for the sake of the oil obtainable from its liver. Note the keel by the side of the tail.

outline may be likened to that of a torpedo. The FOX-SHARK, or THRESHER, so, often seen on is easily recognised, even athot summer days leaping out of water among the pilchard-shoals, considerable distances, by the disproportionately long upper lobe of the tail-fin. This is the it agreeable toshark which attacks certain of the Whale Tribe. Many who stay at home find cast doubt on the story; but the writer has, in Australian seas, witnessed the sight of two of these sharks flinging themselves on the back of an apparently exhausted whale in such unmistakable circumstances that the only alternative (which the reader may accept, if preferred) is to suppose that they were all congenial playmates. it Before specifying some general characters of this interesting group of predatory fishes, . the BRITISH DOG-FISHES; for the HAMMERHEAD-SHARK.maybe as well briefly to sumjnarige very common in southern seas, is so rare a visitor to Britain as to be negligible in an epitome of the group. The dog-fishes, then, which trouble fishermen are the SMOOTH HOUND

Sharks and Rays 667

and KOUGII HOUND, the NURSE. the PICKED DOG, and the SILVER DOG, or TOPE. The NURSE and EOUGH HOUND are spotted leopards of the sea, and the latter has a very curious property. If a fresh- " caught row-hound," as the fishermen pronounce the name, be put in a basket or boat's well with pollack and other fishes, the points of contact will be marked by discoloration of its neighbours. This is probably due to some acrid and bleaching secretion of the row-hound's skin, for which some economic use rholoby IP. Saville-Kent, F.Z.S.] [MUj'ord-on-Sea. might possibly be found. The

OCELLATED DOG-FISH. PICKED DOG, or SPUR-DOG, has

So called from the presence of the eye-like spots on the body, two of which can be seen above very sharp spines in front of the breast-fins. both back-fins, and has therefore to be handled by the fishermen very cautiously, often punishing their hands badly when entangled at night in the nets. Of SMOOTH HOUNDS there are two species or varieties, between which there is some confusion, and in one at any rate there are interesting anatomical peculiarities in the unborn fish (like many other sharks and dog-fishes, the smooth hound bears living young instead of depositing eggs), any account of which would obviously be out of place in so short a description.

Generally speaking, then, the sharks are cartilaginous fishes, having the upper lobe of the tail larger than the lower, a shovel-shaped snout, and the crescent-shaped mouth beneath the head. Another peculiar feature of the group is the presence of breathing-spiracles behind the eyes; while the latter have a manner of blinking not found in other fishes. Of the teeth, which differ in structure from those of other kinds of fishes, there are several rows. The gill-openings are lateral, and usually number five, though one species has six and another seven. With the exception of the afore-mentioned BASKING-SHARK and the PORT JACKSON SHARK, which the writer met with in Australia, they are all more or less dangerous; and when of insufficient size to be harmful to man, do great damage photo by A. s. Rutland & sm* among the lines and nets of INDIAN STRING-RAY. the fishermen. Indeed, the The tail is armed with a powerful poison-spine.

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