THE Natural History of Animals has always been a most interesting and instructive subject, and its popularity increases year after year. It is a branch of knowledge which is entertaining at every age, and it is a favourite study with men of every race and country, and of every intellectual capacity. All children delight in having their little tasks associated with pictures of animals, and the alphabet is learned all the more readily by its being illustrated with spirited drawings of household pets and the terrible creatures of the woods. The marvels of the intelligence of the dog and horse are inexhaustible sources of delight to young readers; and there are few greater pleasures than those which are felt when living animals, whose descriptions and habits have been the subject of instruction and amusement, are seen in some large menagerie or zoological gardens. On the whole, it is probable that few books are so interesting to young men and women as those which relate to animals, and it is their study which, in the majority of instances, leads to the desire for further knowledge of Natural History. The young student soon begins to yearn for information regarding the manner in which different creatures live; how some breathe air, how others live in water; how it is that some fly and others crawl; and he desires to connect the peculiar construction of animals with their method of life. Or he may be content with endeavouring to understand the names of animals, and the reasons why they are arranged or classified in a particular manner by scientific men.

As years roll on, if the interest in Natural History has not diminished, the man, with increasing intelligence and scope of reading, masters the knowledge desired in his youth, and has the opportunity, should he care to grasp it, of the highest intellectual enjoyment. He can enter into the consideration and discussion of the mysterious problems of life: of its origin; of the reasons why animals differ; why they are distributed here and there, or limited in their position in the world; what connection there may be between those of the past and of the present, and of the relation between the creation and the Creator.

Besides this, even should he not aim so high, the man who has had a slight training in Natural History often employs his knowledge for the benefit of art and commerce. How beautiful are the representations of animals on some old coins, how grotesque are those on others! Yet the most correct, and, therefore, the most beautiful, were the result of the careful study of Nature. What benefits to men have resulted from the production of certain breeds of horses, sheep, and oxen! But it has been the study of Nature, and of the laws of the powers of inheritance, which led to most of these results: and thus the practical man is dependent upon the student for his success.

Notwithstanding the interesting nature of the study of the Natural History of Animals, there is certainly more interest taken in it during early life than later on. As a rule, men have no time for it, or they find that, after gaining a certain amount of knowledge, they must study hard if further progress is to be made. Moreover, the vast amount of useless things which had to be learned at school and college have no relation to Natural History, except, perhaps, to convey erroneous ideas and to teach fables, so that this important science has generally to be begun in earnest after the usual education has been completed. When the determination has been made to learn the Natural History of Animals, the student will have to study two separate, yet inter-dependent, branches of knowledge, namely, Zoology and Comparative Anatomy: for the one considers the external shape, habits, distribution, and classification of animals, and the other refers to their internal construction, anatomy, and physiology, and the relation which the internal parts bear to the external in the scheme of classification. These studies are evidently inseparable.

Now, it is the fact that, owing to the importance of Comparative Anatomy to those who study the Anatomy of Man, it is much more frequently learned than simple Zoology. Comparative Anatomy is useful to the medical man, but Zoology is not, and therefore the majority of students whose previous education has led them up to Natural History care but little for the classificatory part. It is equally true that the names and the apparently complicated methods of expression used by zoologists deter most people from the study. If this is a correct view of the relation of the Natural History of Animals to our education, and to the advance of our intellectual culture, it is evident that there is a weak point in the method of the instruction of this charming science during that age when young people begin to inquire for more solid information. The story-book has been read, and the heavy work on Zoology and Comparative Anatomy is as yet sealed, and hence books are required in advance of the one which will lead up to the other; books which—whilst they entertain—instruct and convey, in simple language, the results of the best and latest scientific inquiries. This kind of literature should, moreover, be sufficiently meritorious to attract the general reader who may desire information in any particular portion of the Natural History of Animals.

The book of which this is the Preface has been written in order to obviate the difficulties which have been alluded to, and to form a useful and entertaining Natural History of Animals. It is the result of the work of several English naturalists—of men who have felt the want of such a book in their own studies, and who have had to encounter the difficulties which it is trusted that it will remove. Every endeavour has been made to explain the most interesting facts simply and correctly, and to unite the studies of Zoology and Comparative Anatomy. The anecdotes of the instinct and habits, and of the methods of the capture of animals, have been given so as to illustrate particular gifts and the actions of important organs and structures.

The plan of this Work is not to open with a classification of animals, the majority of whose names and shapes are entirely unknown to the reader, but to describe the shape, nature, and habits of groups of creatures, and then, when they have become familiar, to arrange and classify them. In a popular work it seems more desirable to proceed upon a plan of this kind, than to lead off with an introduction dealing with the nature and importance of Natural History studies, with the abstract ideas of classification, and with the explanation of the necessity of dividing the Animal kingdom according to the principles of Comparative Anatomy. For, obviously, such an introduction would to a large extent defeat the very objects with which this Work has been undertaken.

It is necessary, however, to make a few observations on what is termed classification and its nature. Animals are classified by their resemblances and differences. Those creatures which resemble each other more than others are grouped together, and are separated from dissimilar groups. The first act in classification is to distinguish one animal from others by differences in the shape and internal construction, and the second is to group together the beings whose differences are small. A kind or species is a letter of the Zoological Alphabet, and it is usually said to refer to beings which produce others like unto themselves. A genus is a group of species closely resembling each other; a word in zoological language made up of few or many letters of the alphabet. There may be few or many species in a genus, and whilst some of them very closely resemble each other, others are not quite so much alike; and these link on one genus to another. The notion of a genus is to include a number of kinds in a group which has a character given to it: that is to say, certain peculiarities of shape and of anatomy. It will be obvious that the genus is an artificial affair, and is necessary for the purpose of making science easy.

In order to explain this, look at a domestic cat, a lion, a tiger, a leopard, and a cheetah, and it will be observed that there are differences between them in shape and colour which cause them to be separated into distinct SPECIES. They all have some points of construction in common; and, therefore, they are classified together as five species of a GENUS—the genus Felis.

Then consider the figure and colour of a hyÆna, and of a civet, and study their internal anatomy, and it will be found that although there are differences between them which are sufficient to necessitate the placing of the hyÆnas in one genus (HyÆna), and the civets (Viverra) in another; yet the genera are closely united or allied, in consequence of their possessing many similarities.

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.