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ON THE

DIFFERENT TRIBES OF ANIMALS.

When thy amazing works, O God!

My mental eye surveys,
" Transported with the view I'm lost

In wonder, love, and praise !"

Above fifty thousand species of animals have been detected and described by naturalists, besides several thousands of species which the naked eye cannot discern, and which people the invisible regions of the waters and the air. And,

as the greater part of the globe has never yet been thoroughly explored, several hundreds if not thousands of species, unknown to the scientific world, may exist in the depths of the ocean, and in the unexplored regions of the land. All these species differ from one another in colour, size, and shape; in the internal structure of their bodies, in the number of their sensitive organs, limbs, feet, joints, claws, wings, and fins; in their dispositions, faculties, movements, and modes of subsistence. They are of all sizes, from the mite and the gnat, up to the elephant and the whale; and from the mite downwards to those invi

sible animalcules, * a hundred thousand of which would not equal a grain of sand. Some fly through the atmosphere, some glide through the waters, others traverse the solid land. Some walk on two, some on four, some on twenty, and some on a hundred feet. Some have eyes furnished with two, some with eight, some with a hundred, and some with eight thousand distinct transparent globes for the purposes of sight.

The eyes of beetles, silk worms, flies, and several other kinds of insects, are amongst the most curious and wonderful productions of the God of nature. On the head of a fly are twolarge protuberances, one on each side; these form its organs of sight. The whole surface of these protuberances is covered with a multitude of small hemispheres, placed with the utmost regularity in rows, crossing each other in a kind of latticework. These little hemispheres have each of them a minute transparent convex lens* in the middle, each of which has a distinct branch of the nerve belonging to sight ministering to it; so that the different lenses may be considered as so many distinct eyes.

* ANIMALCULES, from the Latin word animalculum, a very small animal. Generally applied to animals too small to be seen without the aid of a microscope.

* Convex, from the Latin word convexus, rising in a circular form.

Lens, from the Latin word lens, a bean, is properly a small roundish glass of the figure of a lentile, or small flat kind of bean. The meaning however is now extended. Lenses are not now necessarily glass, nor shaped like a bean, but may be made of other forms, and of any transparent substance. A burning glass, spectacle glass, or an object glass of a telescope, is called a lens. Also a particular coat of the eye which has a magnifying power.

Mr. Leuwenhoek counted six thousand two hundred and thirty six in the two eyes of a silk-worm, when in its fly state; three thousand one hundred and eighty in each eye of a beetle; and eight thousand in the two eyes of a common fly. Mr. Hook reckoned fourteen thousand in the eyes of a drone fly, and in one of the eyes of a dragon fly there have been reckoned thirteen thousand five hundred of these lenses, and, consequently, in both eyes, twenty-seven thousand; every one of which is capable of forming a distinct image of any object, in the same manner as

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