of those beautiful little tropical fishes called Chaetodons. In the East Indies these are kept in vases for the purpose of witnessing their unerring archery, as their feats in this way are highly amusing. The manners of these little fishes (abundantly confirmed by subsequent testimony) were first described by Dr Schlosser, in a communication to the Royal Society, on the authority of Mr Hommel, the Governor of the Hospital at Batavia.

The little fish alluded to (Chelmon rostratus) "frequents the shores and sides of the sea and rivers in search of food when it spies a fly sitting on the plants that grow in shallow water, it swims on to [within] the distance of

four, five, or six feet; and then, with a surprising dexterity, it ejects out of its tubular mouth a single drop of

water, which never fails striking the fly into the sea, when it soon becomes its prey.

"The relation of this uncommon action of this cunning fish raised the Governor's curiosity; though it came well attested, yet he was determined, if possible, to be convinced of the truth by ocular demonstration. For that purpose he ordered a large wide tub to be filled with seawater; then had some of these fish caught and put into it, which was changed every other day. In a while they seemed reconciled to their confinement; then he determined to try the experiment.

"A slender stick, with a fly pinned on at its end, was placed in such a direction on the side of the vessel as the fish could strike it. It was with inexpressible delight that he daily saw these fish exercising their skill in shooting at the fly with an amazing velocity, and never missed their mark."*

* "Phil. Trans." for 1764, vol. liv., p. 89.

CHAPTER XXIX.

AMPHIBIA (Frogs and Toads).

"To any person," observes the eloquent historian of British Reptiles, "capable of appreciating the interest attached to the study of physiological phenomena, the contemplation of an animal which at one period of its life is endowed exclusively with the organs of aquatic respiration, resembling the gills of fishes, with means of locomotion adapted only to a constant residence in the water, and with a digestive apparatus fitted exclusively for the assimilation of vegetable food, assuming by degrees the function of atmospheric respiration, acquiring limbs which are formed for leaping on land with great strength and agility, and manifesting the most voracious carnivorous appetite, will not only excite feelings of the deepest admiration, but necessarily lead to the investigation of the laws by which such extraordinary changes are governed, and of the relations which they bear to the theory of continuous affinity, and to that of progressive development through the whole of the animal kingdom."*

Such phenomena are exhibited by the Toads, Frogs, and Newts, the familiar representatives of that limited

* Bell's "Brit. Rept.," p. 72.

Class of animals whose scientific appellation we have inscribed at the head of this chapter. They thus afford a beautiful link in that tissue of "chain-mail" which constitutes the Plan of Nature; for they evidently hold an intermediate position between the FISHES, whose respiration is exclusively aquatic, and the true REPTILES, in which this vital function is exclusively aerial.

Let us look a little more closely at this curious point,— the metamorphosis which the AMPHIBIA undergo, and the accompanying change in the character of their breathing organs. In the month of April, in almost every ditch and pool in the country, we see large masses of clear jelly, with black dots distributed at even distances throughout, or long strings of the same substance, in which the black dots are arranged in a double row. The former is the spawn of the Frog, the latter that of the Toad; and each dot is the maturing embryo of a single egg, which latter is a clear globe of about one-fifth of an inch in diameter. When the spawn is laid, the embryo is an opaque globule, darker at one side than at the other. In a few days, however, this begins to take the form of an animal-the head, the body, and the tail being distinct, as the little creature lies on its side within the egg, coiled up in a semicircle. Soon a kind of wart buds from each side of the neck-the future gills; and currents of water are seen to stream to and from these important, but as yet minute, organs.

As time passes, the gills divide into branches, the nostrils and the eyes appear, and traces of the mouth may be discerned. Meanwhile, the power of voluntary movement, at first confined to the head and tail, increases; and the

little prisoner, as if impatient of confinement, tries to straighten itself by spasmodic efforts, and at length succeeds in rupturing the skin of the egg and becomes free.

It is now a Tadpole-a fish-like creature, without limbs, with an enormous head, and a body thinned off to

Transformations of Frog.

a long tail, which is furnished with a broad finny expansion above and below. The gills now attain their greatest size, and consist on each side of a pair of much-branched tufts, which, under the microscope, present a most inter