Coloration Of Some Animals
( Originally Published Ealry 1900's )
WHEN the meaning and purport of the coloration of mammals first began to receive careful attention on the part of naturalists, there was a tendency to classify brilliant markings like those of the African bushbucks, bongo, and kudus as " recognition markings "—that is to say, markings designed to enable all members of a species to recognise with facility their own kind. Animals have, however, other modes of mutual recognition in addition to colour; besides which different species, whether they go about in pairs, in small family parties, or in herds, keep, as a rule, more or less to themselves, and are in no danger of mistaking other species for their own kind.
Probably among the great majority of mammals the only recognition marks " are the white or light-coloured areas on the tail or hindquarters, which are displayed to their fullest extent in many cases when the members of a party or herd have to " bolt " suddenly to cover. In some species, like the rabbit and the white-tailed American deer, the white area is restricted to the underside of the tail and the adjacent portions, and in such cases the tail is always raised when in flight, so as to expose a large and conspicuous blaze of white. In other species, such as the Japanese deer and its relatives of the Asiatic mainland, or the roe, the white area takes the form of a patch of long hairs on the same parts, which are erected and expanded when the animals are alarmed. Probably the straw-coloured patch of the wapiti and red-deer is of the same nature, but as these animals are less likely to miss their leader when in flight than is the case with smaller species, the " recognition mark " is less conspicuous.
In regard to spotted deer and striped antelopes, it seems probable, as has been suggested by Mr. R. I. Pocock, that the white markings belong to two different categories so far as their purpose is concerned. In many of such animals not only is the under-surface of the body white, but there are several white gorgets on the throat and white spots on the side of the face and chin. Now there can be little doubt that such white areas are for the purpose of counteracting the dark shade thrown by the body, and thus rendering the animal much less conspicuous when seen at a distance than would otherwise be the case. That this is the true explanation is rendered practically certain by the circumstance that such white markings, especially the gorgets on the throat, persist in species which, like the Indian nilgai and the American prongbuck, have lost the ancestral stripes and spots. In neither of the two species referred to, it may be well to observe, are the young spotted or striped, and it is there-fore only from analogy that we speak of their ancestors being thus colored; but the nilgai is so closely related to the bushbucks and kudus that there can be little doubt that the assertion is justifiable. Even, however, if it were not so, the case as regards the purport of the white gorgets and under-parts remains unaltered. It may be added that such white patches can only be effectual where there is plenty of light to throw the shadow; and this is in accordance with the fact that kudu and chital inhabit less dense forest than sambar.
Having indicated, then, the special purpose of the white under-parts and throat-markings of deer and antelopes, we may consider the object of the stripes and spots characteristic of certain species and groups. All the bushbucks, save the males of one or two species, together with their near relatives the bongo, the kudu, and the elands, are characterised, as a rule, by having the whole body marked by narrow white stripes, which are, for the most part, vertical (although in some cases they form a kind of network) upon a fawn or rufous ground. And these animals, as is attested by the large size of their ears, are chiefly dwellers in forest. Directly, however, any member of the group has left the forest for more open country, as in the case of the Cape eland and the Cape bushbuck, the stripes more or less gradually disappear. Further, those species which inhabit the densest forest have their colours the most brilliantly developed, as is well exemplified in the case of the lesser and the greater kudu, the former of which is more of a forest animal than the latter. One of the most brilliantly coloured of all is the bongo of the equatorial forests.
Clearly, then, narrow vertical white stripes on a fawn or chestnut ground, which we have reason to regard as a very primitive type of animal coloration, are connected with a forest life, and the presumption is that they are of a protective nature. Confirmation of this view-if confirmation be needed-is afforded by two animals be-longing to widely different groups—namely, Grévy's zebra and the Somali giraffe. The former of these animals differs from all its kindred by its enormous and heavily fringed ears, and these proclaim it to be a dweller in brushwood or forest rather than in. open plains, a supposition which receives definite confirmation by the photographs taken during Lord Delamere's East African journey. But Grévy's zebra likewise differs from all its kindred by the extreme narrowness of its stripes, white stripes alternating with black ones of the same width. Here, then, narrow white stripes are clearly an adaptation to a forest life. And we further learn, from contrast with the bushbucks, that when the ground-colour is fawn or rufous the intervals between the white stripes must be large, while in the case of a black ground such intervals are no greater than the width of the stripes.
Whether such modifications of the pattern according to the shade of the ground-colour produce the same effect in forest or brushwood, can be learnt only by actual observation, and here again we must look to the sportsman.
As regards the Somali giraffe, those who have had the opportunity of seeing Lord Delamere's photographs ear scarcely fail to notice that the type of coloration differs markedly from that of the common species, while the animal itself appears to be found in much more jungly country than is the case with the former. In place of having a buff ground-color blotched with large irregular chocolate patches, the Somali giraffe is a liver-colored animal marked with a coarse network of fine white lines, the type of coloration coming very close to that of some of the smaller bushbucks. Clearly this coloring is an adaptation for a mode of life not very different from that of the bushbucks, whereas the coloration of the ordinary giraffe is suited to an animal dwelling in open plains dotted here and there with tall scattered trees. The two types of coloration are, in fact, precisely analogous to those of Grévy's zebra as compared with Burchell's zebra, the one being a dweller in brushwood and the other in open country. The Somali giraffe has not, how-ever, acquired the broad ears of essentially forest animals like its cousin the okapi, and for a very sufficient reason. The brushwood amid which this giraffe is commonly found does not reach more than halfway up its neck, as is clearly shown in the photographs already alluded to, so that ears of ordinary size suffice for the creature's hearing.
The mention of the okapi recalls the fact that the coloration of the upper part of the legs and hindquarters takes the form of narrow black and white stripes, running, however, more horizontally than vertically, but evidently conforming to the characteristic forest type.
From the foregoing observations it seems evident that in Africa, and in that country alone (for there are no vertically striped ungulates in Asia), there are two distinct types of protective coloration, the one generally associated with large ears, for animals frequenting forest or brushwood, and the other for those living in more open country. The forest type takes the form of white stripes, either upon a fawn or chestnut or upon a black ground (the dark intervals being broad in the former case and narrow in the latter), or of a white net-work upon a liver-coloured ground. On the other hand, in the plain type we have either an alternation of broad dark and light vertical stripes or dark blotches upon a buff ground. Both forms of the latter type have been definitely stated to render the animals in which they occur more or less inconspicuous at comparatively short distances. But, so far as I am aware, there are absolutely no observations to indicate the degree of invisibility in the wild state of the two modifications of the forest type. Probably, however, the alternations of dark and light vertical stripes harmonise with the vertical lines formed by stems of underwood and the spaces between them.
We also want to know whether either or both of these types of apparently protective coloration are for their special purpose as good as (or better than) a uniform coloration, or under what circumstances, if any, the latter is superior to the former. For, curiously enough, both the forest and the plain type of coloration appear to have been transformed, in some instances, into a uniformly colored coat. As regards the plain type, the now extinct quagga shows the partial loss of the stripes, which have completely disappeared from the wild asses of Northern Africa. Very remarkable is the circumstance that from a fully striped animal like the so-called Grant's zebra of Abyssinia there is a complete graduation to the typical Burchell's zebra of the Transvaal, in which the stripes have disappeared from the legs, and the dark stripes are intercalated with paler " shadow stripes." One step from this animal and we reach the quagga, which, be it noted, inhabited the same country as the uniformly colored Cape eland. Evidently in the Cape district both the forest and the plain types of striping were unsuitable and tended to disappear. In the North African wild asses the disappearance of the striping is complete. Before we can attempt to explain this it is necessary to know whether a Grant's zebra and a wild ass are equally inconspicuous in their own particular habitats, and whether any difference in this respect would be noticeable if the one were transported to the habitat of the other.
An instance of the replacement of the forest type of striping by a uniform coat (otherwise than in the case of a desert-dwelling species) is afforded among the bush-bucks by the males of the nyala, which have long, shaggy brown coats with but very indistinct traces of striping. Is this dark coat a better protection than the brilliantly striped one of the female, or is it assumed because the males have (on account of their horns) no longer any need of protection? On the other hand, it is due to the fact that the bucks keep more to the heart of the forest, and are more nocturnal than their partners?
Another phase of coloration for the development of which no satisfactory reason can be assigned, is presented by the males of certain ruminants, such as the Indian blackbuck, the white-eared kob, and Mrs. Gray's kob of the White Nile, and the banting, or wild ox, of Java. In all these four species (the first three of which are antelopes) the adult males exchange the foxy red coat of the younger members of their own sex and of the females at all ages for a sable livery relieved by larger or smaller white areas. Clearly this coloration, in place of being protective, renders the animals in which it occurs conspicuous. The only suggestion which seems at all reasonable is that it must either be a " warning color " or one adapted to attract females towards the leader of the herd. If it come under the former category, it has apparently been developed in order to deter other animals from attacking the leaders of the herd, on account of their prowess in fight. That such an immunity would be an advantage to the individuals in question cannot be doubted; and possibly it receives support from the circumstance referred to in the next paragraph.
Although both sexes of the banting carry horns, the females of the aforesaid three species of antelope are hornless. In certain species, such as the sable antelope of Africa and the gaur (the miscalled bison) of India, in which both sexes are horned, the adult females as well as the males have assumed a blackish coat; and, so far as it goes, this phase is in favour of the view that the acquisition of a sable livery by certain species is for the purpose of warning off foes, both sexes in the above instances having formidable weapons of offence and de-fence, and being thus perfectly capable of taking care of themselves.
Probably the black hue of the Asiatic buffaloes and of the typical race of their African relatives was originally developed in the same manner and for the same purpose as in the case of the sable antelope. It may, however, now have acquired a higher significance, and be connected with the general prevalence of blackness among large hoofed mammals, such as elephants, rhinoceroses, hippopotamuses, buffaloes, and, to a great extent, tapirs. Among such animals it will not fail to be noticed that in many instances both sexes are armed with either horns or tusks ; and that where such weapons have been discarded the animals are sufficiently protected either by their huge bodily bulk or by the nature of their haunts. Although we have the testimony of many sportsmen as to the difficulty of seeing an Indian elephant, even at close quarters, when in thick covert, we have yet to learn whether the prevalence of a black or dark grey skin among so many of the larger mammals is or is not for the purpose of protection. But since large herds of animals thus colored are frequently to be met with in open country, it has probably been developed for some other purpose, although what this may be it is difficult even to conjecture.
Returning once more to deer, and taking first the case of the fallow-deer, which (with the exception of the dark race) is spotted in summer and uniformly colored in winter, there seems no doubt that the dappled summer coat is for the purpose of harmonising with the checkered shade cast by the leafy boughs of the trees under which the animals are wont to repose. This harmony has doubtless been noticed by many of my readers, and is well expressed in the following passage from Dr. L. Robinson's " Wild Traits in Tame Animals," which refers to a scene in Greenwich Park:
" The dappled fallow-deer were. grazing among the chestnut-trees or lying down upon the soft grass. I sat down on a seat to watch them, determined, if possible, to learn something fresh from them before I moved from the spot. One could not help noticing how remarkably their mottled skins, angular outlines, and branching horns fitted them for concealment in the glades of the forest. Even here, where the surroundings were to a large extent artificial, every now and then the eye would suddenly chance upon a deer resting among the checkered shadows, which was so inconspicuous that it had previously escaped notice."
Assuming, then, that the object of the dappled coat is to harmonise with the splashes of sunlight and shade beneath forest trees in summer, it is perfectly obvious that in temperate latitudes such a type of coloration would be quite out of place in winter, when the forest trees have shed their leaves. Accordingly the. fallow-deer exchanges its dappled summer livery for a uniform coat of fawn more in harmony with the sombre color prevalent in nature generally during the northern winter. A precisely similar change takes place in the Japanese deer and its relative, the Peking deer of Manchuria, both of which have bright chestnut coats dappled with large white spots in summer, while in winter they are clothed in somber brown. It is, moreover, noticeable that in the Peking deer the summer coat is exchanged for the winter dress comparatively early in the season—doubtless in correlation with the early advent of winter in its native habitat.
The Japanese and Peking deer have, however, a representative in the island of Formosa, which lies just on the northern tropic. Now, this Formosan deer or Formosan sika, as it is properly called—differs from its northern relatives by retaining its spots more or less distinctly throughout the winter- obviously in correlation with its southern domicile, where perpetual summer reigns.
But, as being probably descended from northern representatives of the group, the Formosan sika has not been able to get entirely rid of the change from a spotted to a uniformly colored coat. On the other hand, the chital, or spotted deer of India, which is essentially a tropical or subtropical form, is just as brilliantly colored and as fully spotted in winter as in summer.
Regarding the haunts of the chital, Dr. Blanford, in " The Fauna of British India—Mammals," writes as follows: —
" The especial habitat of this deer, perhaps the most beautiful in form and coloration of the whole family, is amongst bushes and trees near water and in bamboo jungle. Indian plains and lower hills, on the margins of rippling streams with their banks overgrown by lofty trees, or in the grassy glades that open out midst the exquisite foliage of bamboo clumps. Spotted deer are thoroughly gregarious, and associate at all times of the year in herds, sometimes of several hundreds. They are less nocturnal than sambar, and may be found feeding for three or four hours after sunrise, and again in the afternoon for an hour or two before sunset. They generally drink between eight and ten o'clock in the morning, the time varying with the season of the year, and repose during the day in deep shade."
From this account it is clear that the habits and haunts (allowing for the difference in foliage and scenery) of the chital are practically the same as those of the fallow-deer in summer. Both species frequent forest glades in large herds daring the daytime, and seek repose under the shade of spreading trees. It may be added that another species of spotted deer inhabiting the tropics namely, the Philippine spotted deer—resembles the chital in retaining its dappled livery at all seasons.
From these facts it is safe to conclude that among the members of the deer tribe a white-spotted coat is a protective adaptation to a diurnal life among the glades of leafy woods. When such woods, as in the tropics, retain their foliage throughout the year, the deer likewise retain their spots. On the other hand, when, as in the northern temperate zone, the trees become bare and leafless. in winter, the deer assume a dull-colored uniform livery in harmony with the somber conditions of their inanimate surroundings.
One other point in connection with the above-mentioned species of spotted deer deserves brief mention. All of them, whether spotted in summer only or throughout the year, have " recognition marks " on their hindquarters. In the fallow-deer and chital these take the form of a white under-surface to the tail and white on the adjacent portion against which it rests, while in the sikas there is a patch of extensile white hairs. When the tail is raised in flight, as is always the case, a large white " blaze " is displayed, which serves not only to indicate the direction in which to fly, but likewise as a danger signal to the entire herd. Evidently these strongly pronounced " recognition marks," which are not developed in nocturnal and thicket-haunting deer of the sambar type, are correlated with the habit of frequenting the outskirts of glades of forests during daylight in large herds.
The various races of the sambar which have exchanged the primitive spotted coloration of the chital for a dull brown and shaggy coat are proclaimed to be essentially animals of the thick forest by the large size of their ears, although this characteristic is more strongly marked in the larger than in the smaller races of the group. Dr. Blanford's account of the habits of the Indian sambar runs as follows : —
" This is the woodland deer of South-Eastern Asia generally, and is more widely and generally distributed than any other species. . . It comes out on the grass slopes when such exist, as in the Nilgiris and other hill-ranges, to graze, but always takes refuge in the woods. It is but rarely found associating in any numbers; both stags and hinds are often found singly, but small herds of four or five to a dozen in number are commonly met with. Its habits are nocturnal; it may be seen feeding in the morning and evening, but it grazes chiefly at night, and at that time often visits small patches of cultivation in the half-cleared tracts, returning for the day to wilder parts, and often ascending hills to make a lair in grass amongst trees, where it generally selects a spot well shaded from the sun's rays."
Contrasting this with the account given above of the mode of life of the chital, the reason of the color of the sambar will be apparent. It is essentially a deer of the thickets, nocturnal and more or less solitary in habits, and shunning the sunlit glades. Hence not only is the coat uniformly dusky brown, but the white " recognition marks," so useful in the case of the fallow-deer and the sikas, are entirely wanting.
As regards the change from a grey fawn-color in summer to a foxy red in winter exhibited by many kinds of deer—most markedly by the American white-tail and the European roe, and, in a somewhat less degree, by the (red-deer — it seems to be certainly analogous to the change from a spotted to a uniform coat in the Japanese and fallow-deer, and must therefore be for the purpose of protection. Prima facie, it might have been thought that the winter dress would be red, since this tint would apparently harmonise well with the russet hue of fallen leaves and dead bracken. The tone of the summer dress is, however, very similar to the ground-color of the coat of the Peking and Japanese deer at the same season, although we have yet to learn why a uniformly red tint is more advantageous in the ease of the roe and the white-tail than a spotted dress. Possibly it may be owing to the more open nature of the country frequented by these and other species in which this type of coloration pre-Mails.
That the change in the roe, the red-deer, and the white. tailed deer from red in summer to grey in winter is analogous to the change from a spotted to a uniform coat in the Peking deer and the fallow-deer, is demonstrated not only by the nature of the color itself, but more emphatically by the circumstance that in tropical and subtropical countries red-coated deer, such as the Indian muntjac and swamp-deer, or barasingha, retain their color throughout the year. A similar condition is noticeable in the case of the small tropical representatives of the Virginian white-tailed deer, most or all of which do not change their color with the season. In the last-mentioned instance it appears, indeed, that the coat is brownish or greyish, instead of red; but it is quite clear that the change from a red summer coat to a grey winter dress in species like the white-tail and the roe is for the purpose of protection, and is correlated with the presence of foliage on the trees at the one season and its absence at the other. It may be added that the white-tail and the muntjac have the under-side of the tail and the inner surfaces of the adjacent parts white, and thus display a conspicuous patch when running to covert with the tail elevated. Somewhat curiously, the roe generally develops a white patch only when in the grey winter dress.
In those animals whose fur is ornamented with dark or light markings, these markings generally take the form either of longitudinal or transverse bands, or of spots; the latter being frequently arranged in more or less distinctly defined longitudinal lines, but never in transverse bands. Moreover, these markings, especially in the case of stripes and bands, are generally most developed on the upper surface of the body, although spots may be equally present on both the upper and the lower surfaces of the body. Many mammals, again, whether they be spotted or whether they be striped, have their tails marked by dark rings on a light ground; but this feature is also present in others in which the color of the body is of a uniform tint. It must not, however, be supposed that there is any sharply defined distinction between spotted and striped mammals, many of the civets, as well as some of the cats, having markings intermediate between true spots and stripes. Spots, again, are some-what variable in configuration, sonie animals, like the hunting-leopard, having solid circular dark spots, while in others, such as the leopard and jaguar, they assume the form of dark rings enclosing a light center. In some cases, as in the giraffe, the spots are enlarged so as to form large and more or less quadrangular blotches.
A survey of a museum or a menagerie will likewise show that spots and stripes are by no means equally prevalent in all groups of mammals. In the apes, monkeys, marmosets, and lemurs, for instance, they never occur; and when these animals are diversely colored, the coloration takes the form of patches symmetrically disposed on the two sides of the body, but otherwise not following any very clearly defined mode of arrangement. Then, again, in the hoofed mammals, many species are more or less uniformly colored, although the zebras are notable instances of transversely striped animals, while the giraffe is an equally notable instance of the blotched type of coloration. Among the even-toed subdivision of this order it may be also noticed that while in the more specialised forms, such as wild cattle and sheep, the coloration is more or less uniform, many of the antelopes show white transverse stripes on a dark ground.
Dark transverse stripes are, however, known only in the case of the little zebra-antelope of western Africa, and the gnus; while, although a lateral dark flank-stripe is present in some antelopes, and in the gazelles, none of these animals have the whole body marked by longitudinal dark stripes. In the case of the deer it has been mentioned that certain species, like the. fallow-deer and the Indian spotted deer, are marked with longitudinal rows of white spots at all ages ; while in the case of other species it will be found that the young are similarly marked, whereas the adults are uniformly colored. A similar state of things occurs among wild pigs, and also in the tapirs, from which we are naturally led to infer that in this group of mammals, at least, a spotted or striped type of coloration is the original or generalised condition, while a uniformly colored coat is an acquired or specialised feature. And the same holds good for other groups.
Turning to the carnivorous mammals, we find that in many families, more especially the cats, hyaenas, and civets, stripes and spots are far more generally present than a uniform coloration; although some groups, such as the bears, form a marked exception to this rule, the majority of the species being uniformly colored, while none are striped or spotted. In some species of the weasel family—notably the badgers—it may be also noticed that while the sides of the head are marked by longitudinal dark and light stripes, the remainder of the body is uniformly colored. And it may be mentioned here that many animals, such as donkeys and dun-colored horses, retain a longitudinal dark stripe down the back, frequently accompanied by dark transverse bars on the limbs, while a uniform coloration prevails elsewhere.
In the gnawing mammals, or rodents, although many species are uniformly colored, stripes and spots are prevalent; and a survey of the collection of these animals in a good museum will show that, whether the pattern take the form of stripes or of spots, the arrangement is invariably longitudinal and never transverse. Indeed, it may be observed that when spots are present, these are invariably light-colored on a darker ground. Although in many eases the longitudinal stripes occupy the whole or a considerable portion of the upper surface, in some of the squirrels they are reduced to a dark and light stripe, or even a single light stripe on each flank, this remarkable type of coloration recalling the " speculum " on the wing of a duck. .
Several attempts have been made to reduce the coloration of animals to some general law, and among these one of the most notable was published some years ago by Prof. Eimer, of Tubingen, who based his conclusions on a comprehensive study of vertebrates in general. As the result of his investigations, this observer declared that the following laws might be laid down in regard to color-markings of animals in general. Firstly, the primitive type of coloration took the form of longitudinal stripes. Secondly, these stripes broke up into spots, retaining in many cases a more or less distinct longitudinal arrangement. Thirdly, the spots again coalesced, but this time into transverse stripes. And fourthly, all markings disappeared, so as to produce a uniform coloration of the whole coat. As a further development of this theory, it was added that the more specialised features were assumed in many cases more completely by the male than the female, while the primitive coloration often persists in the young. It was also stated that the primitive longitudinal stripes frequently persist on the middle of the back, and likewise on the crown and sides of the face, examples of the latter survival being shown by the head-and face stripes of many spotted cats, and the dark and light streaks on the side of the face of the badger.
If these laws be true, we should, prima facie, expect to find a large number of longitudinally striped forms among the lower members of the class; while those of intermediate grades of evolution would be spotted, and the higher types either transversely striped or uniformly colored. This, however, could only be the case, as a whole, if all the mammals formed one regularly ascending series; whereas, as a matter of fact, they form a number of diverging branches, each containing specialised and generalised forms. The inquiry is thus rendered one of extreme complexity, although there ought, if the theory were true in its entirety, to be a considerable number of longitudinally striped species among the lowest groups of all. Unfortunately, paleontology, from the nature of the case, can afford us no aid, which very materially adds to the difficulty. It may be added that in Prof. Eimer's scheme no distinction is drawn between light and dark markings—that is to say, between the total disappearance of pigment and an ultra-development of the same — and it is obvious that this may be. of such prime importance that these two types of coloration may have nothing whatever to do with one another. Nevertheless, we may provisionally consider light and dark stripes and light and dark spots as respectively equivalent to one another.
With regard to uniformly colored animals, there can be no question as to the truth of the theory, since the young of so many animals, such as lions, pumas, deer, pigs and tapirs show more or less distinct striped or spotted markings, which disappear more or less completely in the adult. The occurrence of bands on the legs and sometimes on the shoulders of mules and dun-colored horses, and likewise the presence of dark bars on the limbs of otherwise uniformly colored species of cats, like the Egyptian cat and the bay cat, are further proofs of the same law. Moreover, the fact that in the young of pigs — and, to a certain extent, those of tapirs —the markings take the form of longitudinal stripes, whereas in the more specialised deer, whether young or old, they are in the shape of spots arranged in more or less well-defined lines, is, so far as it goes, a confirmation of the theory that spots are newer than stripes. And the presence of transverse stripes in the still more highly specialised antelopes tends to support the derivation of this type of marking from spots, especially if it be re-membered that the harnessed antelopes are partly spotted. Still, it must be borne in mind that these in-stances apply only to light markings, which, as already stated, may have a totally different origin from dark ones.
There are, however; apparently insuperable difficulties as regards longitudinal and transverse striping in mammals. In the first place, instead of finding a number of the more primitive marsupials, showing longitudinal stripes, we have in this group only the three-striped and single striped opossums thus marked, and in these the stripes are respectively reduced to the numbers indicated by their names. This, however, is not all, for the banded ant-eater takes its name from the narrow transverse white stripes with which the back is marked; while the thylacine, which cannot in any sense be regarded as a specialised type, is similarly marked with broader dark stripes, neither of these animals having any trace of a longitudinal stripe down the back. The water-opossum, again, may be regarded as a transversely striped marsupial, although here the stripes are few in number and approximate in form to blotches. Although in the same order the dasyures are spotted with white, we have no black-spotted marsupial; and if such a type formed the transition between longitudinal and transverse stripes, surely some species showing such a type of coloration ought to have persisted.
Then, again, in the ungulates we have the zebra-antelopes, the gnus, and the zebras showing most strongly marked transverse dark stripes; but we have no dark-spotted forms in the whole order except the giraffes, while the only ones with dark longitudinal stripes are young pigs. And it would thus appear that, although all the animals above mentioned are highly specialised species, these transverse stripes and dark blotches must have originated de novo quite independently in each of the groups in question. Indeed, when we remember that the coloration of zebras, antelopes, and giraffes is generally of a protective nature— the stripes of the former rendering the animals invisible on sandy ground in moonlight, and, to a great extent, also in sunlight, while the blotches of the latter harmonise exactly with the checkered shade thrown by the mimosa-trees among which they feed — it is incredible that both types should have been evolved, according to a rigid rule, from animals marked by dark longitudinal stripes.
Another instance of the same nature is afforded by the cats, in most of which the coloration appears to be mainly, of a protective nature, plain-colored species, like the puma and lion, having tawny coats harmonising with the sandy deserts which these animals often inhabit, while the vertical stripes of the tiger, although in some degree resembling the perpendicular lights and shadows of a grass-jungle, are probably for the purpose of breaking up the outline of the body. The clouded markings of the marbled cat and clouded leopard assimilate with the boughs on which these species repose, and the spotted coat of the Indian desert-cat renders the creature almost invisible in stony deserts. To suppose that all such adaptations have been produced in the regular order required by the theory is as incredible as in the last case. There is, moreover, the circumstance that the young of the uniformly colored lion and puma are spotted, thus giving an instance of the direct passage from a spotted to a plain-colored form without the intervention of a transversely striped stage, precisely the same thing also occurring in the case of the deer. It should, however, be mentioned that lion cubs occasionally have their tails ringed like that of a tiger, instead of spotted in leopard-fashion; so that in this particular instance transverse stripes are intercalated between the spotted and the uniformly colored stages.
If we look for the most primitive mammals with longitudinal dark stripes over the greater part of the upper surface, such types being wanting in the marsupials, we shall find them in the striped mongooses of Madagascar. And as the civets and their allies are certainly the most generalised of existing carnivora (although the modern members of that order occupy a somewhat high position), this case tends, in a certain degree, to lend some support to the view that longitudinal dark stripes are an early type. The rarity of animals exhibiting this pattern over all their bodies, coupled with the frequent retention of a longitudinal dorsal stripe, are likewise in some degree confirmatory of the same view. With regard to the conspicuous black and white stripes on the cheeks of the badger, and throughout the head and body in the skunks, South African weasel, and Cape polecat, it may perhaps be argued, with some show of reason, that we have an old type of coloration. In the badger this type of coloration is restricted to the face, where it is evidently retained to render the animal inconspicuous among the streaks of light and shadow as it peers out of its burrow. On the other hand, they may have been acquired for this special purpose. In the other forms, all of which are more or less evil-smelling creatures, a conspicuous general coloration is an advantage, as warning off other animals from attacking them in mistake for harmless kinds, and the boldly alternating stripes have accordingly been retained all over the body and rendered as conspicuous as possible.