which owe their occasional noxious qualities to the zoophytes on which they feed.

The poisonous qualities of some shell-fish are, however, attributed by writers on their dietetic properties, to other causes, as we have already shown.*

Why are sea fish sometimes foun1 in fresh water? Because, in forsaking the deep water, aud approaching a suitable spawning station, they leave the sea altogether for a time, ascend the rivers and their tributary streams, and having deposited their eggs, return again to their usual haunts. Even certain species of fish, inhabiting lakes, as the roach, betake themselves to the tributary streams, as the most suitable places for spawning.

Why, in stocking fish-ponds, should the transportation of fish take place only in winter?

Because fish can bear cold much better than heat. Why are fish, as an article of food, well suited for the young, the weak, and the se lentary?

Because it is light, and easily digested; but, for the same reason, it is unsuitable food for those engaged in laborious occupations.

Why is it difficult to preserve fish in glass jars, or small ponds?

Because a great deal of the oxygen in the air contained in the water, is necessarily consumed by the germination and growth of the aquatic plants, and the respiration of the infusory animalculæ. In all cases, when the air of the atmosphere, or that which the water contains, is impregnated with noxious particles, many individuals of a particular species, living in the same district, suffer at the same time.

Why do fishes perish in water that has been boiled? Because the water is then deprived of its atmospheric air, by means of which fishies carry on their respiration.

*See DOMESTIC SCIENCE, page 45.

Why, when fish are steeped in water, does the whole fluid become luminous ?

Because the luminousness appears to be caused by the infusory animalculæ, with which water abounds. -Canton, Phil. Trans.

Why are fish said to be "in season"?

Because the milt and roe are then ripening. After the fish have deposited the spawn, the flesh becomes soft, and loses much of its peculiar flavour. This is owing to the disappearance of the oil or fat from the flesh, it having been expended in the function of reproduction.

When in season, the thick muscular part of the backs, as it contains the smallest quantity of oil, is inferior in flavour or richness, to the thinner parts about the belly, which are esteemed by epicures, as the most savoury morsels.

Why is the reproduction of fishes involved in great obscurity?

Because the element in which they reside conceals from us the actions which they perform, so that we are unable to point out, with certainty, the uses of the different organs, or the functions which they exercise. Even in the days of Aristotle, the difference in the mode of reproduction between the cartilaginous and the osseous fishes had been observed; and although many accurate observations have been made by modern zootomists, much still remains to be done, both in the field of observation and dissection.

In reference to the reproductive system, fishes may be divided into two classes. Thus, some have the sexes distinct, while in others they are united.-Fleming.

RAY-FISH.

Why do the ray genus appear to have contributed to the fable of Sirens?

Because of a certain similarity of the lower part of their head to the human face. Many species have

also been dried, and metamorphosed by a variety of artifices, into supposed basilisks, &c. Although they lay but one egg at a time, they increase so rapidly, that the ocean, in some spots, actually swarms with them. Their eggs have a horny covering with four points, and are called sea-mice.-Blumenbach.

Why is the liver of the skate, cod, and some other fishes, remarkably oily?

Because the rest of their bodies is almost destitute of fat.

Dr. Monro, calculated that the whole gills of a large skate, presented a surface equal to 2,250 square inches; or equal to the whole external surface of the human body.

SHARKS.

Why have most of the sharks very numerous teeth? Because they may supply such as may be lost. The white shark has more than 200, lying on each other in rows, almost like the leaves of an artichoke. Those only, which form the front row, have a perpendicular direction, and are completely uncovered. Those of the subsequent rows are, on the contrary, smaller; have their points turned backwards, and are covered with a kind of gum. These come through the covering substance, and pass forward when any of the front row are lost. The teeth are at first soft and cartilaginous, but gradually become hard as ivory.

The white shark weighs as much as 10,000 pounds, and even whole horses have been found in its stomach. -Blumenbach.

Voracious as are the habits of sharks, the South Sea islanders are not in the least afraid of them. Portlock, the navigator, says: "I have seen five or six large sharks swimming about the ship, where there have been upwards of 100 Indians in the water: they seemed quite indifferent to them, and the sharks never offered to make an attack on any of these people, and

yet at the same time, they would greedily swallow our baits." The perseverance with which sharks follow a vessel at sea, containing a dead body, would prove their nasal organs to be very acute. In a recent

voyage from Bombay to the Persian Gulf, the smell of a dead body of an Arab sailor of a crew, attracted several sharks round the ship, one of which, eight feet in length, was harpooned and hauled on board.

As a curious fact connected with the natural history of the Bible, we may mention that, in 1828, the Rev. Dr. Scot, of Corstorphine, read before the Wernerian Society, a paper on the great fish that swallowed_up Jonah, showing, that it could not be a whale, as often supposed, but was, probably, a white shark. We may observe, that the whale is a gratuitous identity, since the text is "a great fish."—Jonah, c. ii. v. 7.)

Why is the hammer-headed shark also called the balance fish.

Because it has a long obtuse head with eyes fixed at the extremities, and its mouth in the centre. Unlike other sharks, the above is more remarkable for its structure than size, it being little more than 6 feet in length. Why is the pilot-fish so called?

Because it is always found accompanying or preceding the formidable shark.

Why is the saw-fish so called?

Because it has a broad, sword-like weapon in front of the head, with twenty-four or more teeth inserted into its lateral edges.

Why is the sturgeon said to have given rise to the fabulous tales of monstrous sea-serpents of the North?

Because it often happens that many of them follow in a row one after another. The sturgeon is an important fish-as well for its flesh, as for the caviare prepared from its roe. It sometimes weighs nearly 1,000 pounds.-Blumenbach.

Why is the sun-fish so called?

Because of the phosphorescent light of the sides and belly of the living fish. It weighs, occasionally, as much as five cwt.

Why was the sucking-fish formerly believed able to stop a ship in full sail?

Because it can attach itself most firmly, by means of the grooves on the back part of its head, to ships, sharks, &c.

Why is a certain fish called the sea-horse?

Because of the resemblance of its front part to a horse's head and neck. In dying, it bends itself like an S; and then resembles the knight, at chess. Why is the sea-dragon so called?

Because it has large and wide pectoral fins, which resemble expanded wings.

EELS.

Why has the economy of the eel so long exercised the ingenuity of naturalists ?

Because they have hitherto been unable to establish their mode of generation. Lacepède, the French naturalist, asserts, in the most unqualified way, that they are viviparous; but, says Sir H. Davy, "we do not remember any facts brought forward on the subject." Blumenbach says-" According to the most correct observations, the gel is certainly viviparous;" for which he quotes Voight's Neues Magazine. Sir Everard Home, by a course of patient investigation, has ascertained that the common and conger eels, as well as lampreys, are hermaphrodites.

Why do young eels seek fresh water?

Because they prefer warmth, and swimming at the surface in the early summer, find the lighter water warmer, and likewise containing more insects, and so pursue courses of fresh water,-as the waters from the