On comparing the genus Felis with the genera Hyæna and Viverra, it will be noticed that the last two resemble each other more than they do the first, and thus two FAMILIES are formed—one the Felina, to comprehend the genus Felis; and another the Viverrina, to include the genera of hyænas and the civets. But the slight resemblance between these families is sufficient to cause them to be grouped in an ORDER which is called Carnivora, or that of carnivorous beasts.
Again, the Monkeys and Sloths do not resemble each other in shape and internal construction sufficiently to be placed in the same order even, but they and the Carnivora, and many other animals, suckle their young. They may, therefore, be separated, in a classification, from other animals which fly and lay eggs, and do not suckle: as the birds. The Birds form one CLASS, and the Mammalia, or animals that suckle their young, form another. Other Classes are formed by the Reptiles, Amphibia, Fishes, etc.
All the animals of these numerous Classes have a back-bone; but if we examine a nautilus, a snail, a beetle, a worm, a coral, or an animalcule, nothing like an internal skeleton made up of bones, some of which are placed inside the back, can be discovered. Hence all the animals can be arranged into two SUB-KINGDOMS, those with and those without back-bones, or the Vertebrata and the Invertebrata. (The name vertebrata is taken from the Latin word vertebra, which means a turning-joint in the body, or a back-bone.) Those are the sub-kingdoms of the animal KINGDOM, which is so called in contradistinction to the kingdom of plants.
It must be remembered, however, that the best classification is but an attempt of a finite understanding to arrange the infinitely variable things of Nature. It is but an artificial and arbitrary arrangement which is necessary for study: for were the whole truth before us, there would be no classification which would depend on marked differences in shape and internal construction. Were the figures and anatomy of every animal that has lived, and of every creature which is now living on the globe, placed before us, the gaps which enable one genus to be separated from another would be filled up, and even species would cease to be distinguished. But, in spite of the artificial nature of the classifications, there is this to be said of them: that they give some faint indications of the philosophy of creation. The differences and resemblances of animals relate to structures of the body which have been inherited from creatures that lived in the remote past; and we glean this when it is known that the young unborn of one genus resembles the old and fully-formed creatures of kinds belonging to other classes which preceded it in the history of the globe, and when it is shown by the microscope that some of the parts of the bodies of the most insignificant animals of the invertebrate sub-kingdom resemble those of the most gifted of animals.
A classification thus opens out a little of the scheme of Nature, and it proves that the resemblances and differences of animals are not matters of chance, but that there is a law which has produced them. Such a law, yet perhaps not fully comprehended, is Man’s idea of the action of the will of the Divine Creator.
CASSELL’S NATURAL HISTORY.
