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Apart from the birds and the fishes, the vertebrates or backboned animals of the British Islands constitute a very select group. Within the historical period several former notable members of that company have ceased to be represented in the freedom of nature in this country, and their forms can be studied only in museums and zoological gardens. Although we have to regret the absence from our list of the Beaver and the Wild Boar, the Ure-ox and the Short-horned Wild Ox, the Brown Bear and the savage Wolf, there are still sufficient of our vertebrates left to give a zest to the observations of the rambler in the woodlands, over the mountains and along the quiet waysides and streams of our country.

To observe these mammals, reptiles, and batrachians we must go afoot: the bicycle or the motor-car is of use only to convey us quickly out of town to appropriate localities in the open country. Arrived there, quietness must be the order of the day—the footfall light and the voice lowered in conversation if there are two or more in company. The sitter will see far more than the man who wants to perambulate the entire wood or explore the acreage of moorland. A comfortable seat having been chosen with deliberation for the view it affords of a wood margin, a hillside, or stream curve, according to the habits of the creatures we are hoping to see, the field-glass should be brought into requisition, and every inch of the field of vision carefully and repeatedly scanned. The movement of a grass-blade, the trembling of a fern frond or the rustling of a dead leaf will often indicate the precise spot to be watched. It will be understood that as most of these creatures are more or less nocturnal in their activities, observation must be continued until sometime after dusk at least, in order to be successful.

If the observer is new to this work, he should endeavour, if possible—on the first occasion at least—to get as companion a friend who has already some experience of field-work. A day with such a companion will do more to open his eyes than a whole chapter of printed hints; for it is as true to-day as it was in 1855, when Charles Kingsley wrote in his "Glaucus"—"The greatest difficulty in the way of beginners is (as in most things) to 'learn the art of learning.' They go out, search, find less than they expected, and give the subject up in disappointment. It is good to begin, therefore, if possible by playing the part of 'jackal' to some practised naturalist, who will show the tyro where to look, what to look for, and, moreover, what it is that he has found: often no easy matter to discover." On that last point the "Wayside and Woodland Series" has done much to simplify matters.

Respecting the utility of taking an interest in these fellow inhabitants of our country, one of the intellectual giants[A] of the Victorian Age described Natural History "as the greatest of all sources of that pleasure which is derivable from beauty. I do not pretend," he says, "that natural history knowledge, as such, can increase our sense of the beautiful in natural objects. I do not suppose that the dead soul of Peter Bell, of whom the great poet of nature says—

" 'A primrose by the river's brim,

A yellow primrose was to him—

And it was nothing more,'

would have been a whit roused from its apathy by the information that the primrose is a Dicotyledonous Exogen with a monopetalous corolla and central placentation. But I advocate natural history knowledge from this point of view, because it would lead us to seek the beauties of natural objects, instead of trusting to chance to force them on our attention. To a person uninstructed in natural history, his country or sea-side stroll is a walk through a gallery filled with wonderful works of art, nine-tenths of which have their faces turned to the wall. Teach him something of natural history, and you place in his hands a catalogue of those which are worth turning round. Surely our innocent pleasures are not so abundant in this life that we can afford to despise this or any other source of them. We should fear being banished for our neglect to that limbo, where the great Florentine tells us are those who during this life 'wept when they might be joyful.'"

[A] Huxley.

Some of the species described have a very limited range in our country at present, the Deer, for example, being restricted as wild animals to-day to the Scottish mountains and glens and the West Country moors, but even these may be studied as tolerably free animals in the New Forest, Epping Forest, and in many parks such as those at Windsor and Richmond, as well as in private domains. To the Deer we must add the Wild Cat, the Pine Marten, and the Alpine Hare as mammals that must be sought in special restricted areas; but most of the others may be reckoned to be met with, sooner rather than later, in our country rambles.

In view of the practice usual in natural histories of arranging the vertebrate animals in a series with the Birds separating the Mammals from the Reptiles, it may at first sight appear incongruous to bring the latter classes together as we have done; but to the present writer the fitness of this arrangement is quite clear. It is widely held that the Mammalia—the highest class of vertebrates, and therefore the most complex of all animals—have been evolved from an extinct group (Theromorpha) of Reptiles, whose remains are found in strata of the Permian and Jurassic Periods. There are, it is true, similar evidences furnished by the rocks showing that the Birds had a reptilian origin; but the Birds did not form an evolutionary stage between the Reptile and the Mammal, but evolved side by side with the latter.

The existing British Mammals represent the six orders Insectivora (shrews, mole, and hedgehog), Chiroptera (bats), Carnivora (beasts of prey), Rodentia (gnawing animals), Cetacea (whales and dolphins), and Ungulata (hoofed animals). These all agree with the Reptiles and Batrachians in having a many-jointed internal skeleton, a bony framework giving support to a system of powerful muscles; and of this framework the most important feature is the long backbone or vertebral column consisting of a number of bony rings jointed together by outgrowths or "processes," and held in position by strong ligaments. This attachment of the rings by their flat surfaces produces the spine or vertebral column, with a canal on its upper half in which lies the spinal cord. This column, for descriptive purposes, is divided into regions—cervical, dorsal, lumbar, sacral, and caudal. The number of rings or vertebræ in each region varies somewhat in the different classes and orders, but as a rule the cervical or neck vertebræ are seven; the dorsal, to which the ribs are connected, are about thirteen (extreme numbers are nine and twenty-two); the vertebræ of the lumbar or loin region are usually six or seven, but they vary inversely to those of the dorsal from two to twenty-three; the sacral vertebræ (about five) are in the adult fused together into a solid bone (sacrum) of triangular shape; the caudal vertebræ vary from three (man) to nearly fifty, according to the length of tail common to the genus or species.

In front of the neck is the skull, in the Mammals a bony case containing the brain and organs of sense, made up of plates interlocking by their zigzag margins; in the Reptiles and lower vertebrates a more or less open framework. The lower jaw, or mandible, is in adult Mammals the only part of the skull that is separate. Its hinder ends work in cavities on the lower part of the skull, and are held in position by strong ligaments and muscles.

The ribs are attached to the dorsal vertebræ, and connect by cartilage at the other end with the sternum or breastbone—really a series of united bones in the middle line of the chest (thorax). The blade-bones (scapula) of the forelimbs are attached to the upper ribs by the flat or concave side; and the hinder limbs are connected strongly to the sacrum by means of the hip-bones which are united below to form the pelvis, to which the thigh-bone is jointed. The Reptiles and Amphibians exhibit some differences in their skeletal structure which will be pointed out later.

Skeleton of the Common Badger.

View Larger Image Here.

In the matter of teeth there is great diversity among the Mammals—even in the small number of British species. With a view to a proper understanding of the teeth in, say, the Rodents and the Ungulates, it is necessary to write a few words respecting tooth-structure. Although in adult Mammals the teeth are so intimately connected with the jaw as to appear outgrowths from it, this is not the case really. They originate in the skin which covers the jaw, and the most effective part of their structure—the enamel—is derived from the epidermis, the outer layer of the skin. The centre of each tooth is filled with pulp, around which is the bone-like dentine with an outer coat of hard, glossy enamel. In the incisors or cutting teeth of the Rodents, while the front of the tooth is protected by a thick plate of hard enamel, the back portion consists only of dentine which wears away whilst the enamel front maintains a chisel-like cutting edge. In the grinding teeth or molars, especially noticeable in the Ungulates, the enamel is thrown into ridges and tubercles, so that the action of these in the upper and lower jaws upon each other is like that of "the upper and the nether millstones" in grinding corn.

Four forms of teeth are recognised in the Mammals: the incisors in the front of the jaw, the pointed, round canines or "eye-teeth" next to them, and at the sides the cheek teeth, separated into premolars and molars. In describing the teeth in any species a simple formula is adopted which shows at a glance the number of each kind in one side of each jaw. Taking our own normal dental equipment as an example, it would be expressed in this fashion:—

i 2/2, c 1/1, pm 2/2, m 3/3 = 32

the upper figures representing the number of each kind in the upper jaw and the lower figures the teeth of the lower jaw, and the total being reached by multiplying by two for the two sides of the skull. Often in our rambles we may come across the skull of some animal, and an examination of the teeth will help us to the identity of its late owner.

For the purposes of the present work it is unnecessary to enter minutely into all the characters that distinguish the Mammals from the other backboned animals. One is really sufficient—the possession of glands (teats) in the skin of the female which secrete milk for the nourishment of the new-born young. There are, in addition, differences in the structure of the skull and the articulation of the lower jaw. The skin is always more or less clothed with hair. The heart has a single left aortic arch, the blood is hot, and the heart and lungs are lodged in a special cavity separated from the abdomen by a muscular partition known as the diaphragm.

Respecting one item in the foregoing—it has been said truly that the possession of a few or many true hairs as outgrowths from pits in the skin is alone sufficient to distinguish a Mammal from any other animal. Although these hairs may take different forms, they are alike in their origin—even, to take an extreme case, the spines of the Hedgehog. Each hair consists of an outer wall enclosing a central cavity filled with pith, in which is the dark pigment which gives the hair its colour. In the Mammals this pigment is always brown, and the varying tints of the hairs—black, brown, tawny, cream-colour or white—depends upon the amount of pigment and its disposition in the pith, combined with differences in the density of the envelope. In some cases, as about the mouth, eyes, and ears of the Cat, long sensitive hairs are connected with the terminations of nerves, which help the animal to feel its way. There are no marked colour differences in the fur of the sexes, such as we find in the plumage of Birds; though we do find such discrepancies in the presence or absence of horns in Deer, and in the manes and hair-tufts of some exotic Mammals. Certain species, such as the Alpine Hare and the Stoat, undergo a marked seasonal change of colour in the fur under the influence of low temperature. This may be quite sudden, owing to a rapid fall of temperature, and—as shown by Metchnikoff—is effected by the pigment granules being consumed by a sort of phagocyte. By Metchnikoff's researches an old controversy appears to have been settled finally.

ANIMAL LIFE

OF THE BRITISH ISLES.