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When resemblances such as those of the p.r.o.ng-horn are so promiscuously distributed, the task of fixing their values in estimating affinities is not a light one, and in fact the most rational conclusion which we may draw from them is that they point back to a distant and generalized ancestor, who possessed them all, but that in the distribution of his physical estate, so to speak, these heirlooms have not come down alike to all descendants. There is again a complicating possibility that some may be no more than adaptive or a.n.a.logous characters, similarly produced under like conditions of life, but quite independent of a common origin, and it is seldom that we know enough of the history of development of any species to conclude with certainty whether or not this has been the case. At all events, the p.r.o.ng-buck is quite alone in the world at present, and we know no fossils which unmistakably point to it, although it has been supposed that some of the later Miocene species of _Cosoryx_--small deer-like animals with non-deciduous horns, probably covered with hair, and molars of somewhat bovine type--may have been ancestral to it, but this is little more than a speculation. What is certain is that _Antilocapra_ is now a completely isolated form, fully ent.i.tled to rank as a family all by itself.
In the musk-ox (_Ovibos moschatus_), or "sheep-ox," as the generic name given by Blainville has it, we meet with another strange and lonely form which has contributed its full share to the problems of systematic zoology. Its remote and inaccessible range has greatly r.e.t.a.r.ded knowledge of its structure, and it is only within the last three years that acquaintance has been made with its soft anatomy, and at the same time with a maze of resemblances and differences toward other ruminants, that perhaps more than equals the irregularities of the p.r.o.ng-buck. But unlike that species, there is in the musk-ox no extreme modification, such as a deciduous horn, to separate it distinctly from the rest of the family. A recapitulation of these differences would be too minutely technical for insertion here, and it must be enough to say that while it cannot be a.s.signed to either group, yet in the distribution of hair on the muzzle, in the presence of a small suborbital gland, in shortness of tail and the light color of its horns, it is sheep-like; in the absence of interdigital glands, the shortness and stoutness of its cannon bones, and in the presence of a small accessory inner column on the upper molars, it is bovine. But in the coa.r.s.e longitudinal striation of the bases of its horns it differs from both. The shape of the horns is also peculiar. Curving outward, downward and then sharply upward, with broad, flattened bases meeting in the middle line, their outlines are not unlike those of old bulls of the African buffalo.
At the present time the musk-ox inhabits only arctic America, from Greenland westward nearly to the Mackenzie River, but its range was formerly circ.u.mpolar, and in Pleistocene times it inhabited Europe as far south as Germany and France. The musk-ox of Greenland has lately been set aside as a distinct species. The most we can say is that _Ovibos_ is a unique form, standing perhaps somewhere between oxen and sheep, and descended from an ancient ruminant type through an ancestry of which we know nothing, for the only fossil remains which are at all distinguishable from the existing genus, are yet closely similar to it, and are no older than the Pleistocene of the central United States; in earlier periods its history is a blank about which it is useless to speculate.
The last of our three anomalies, the white, or mountain goat (_Oreamnos monta.n.u.s_), is not as completely orphaned as the other two, for it seems quite surely to be connected with a small and peculiar series consisting of the European chamois and several species of _Nemorhaedus_ inhabiting eastern Asia and Sumatra. These are often called mountain antelopes, or goat antelopes. So little is yet known of the soft anatomy of the white goat that we are much in the dark as to its minute resemblances, but its glandular system is certainly suggestive of the chamois, and many of its att.i.tudes are strikingly similar. In all the points in which it approaches goats it is like some, at least, among antelopes, while in the elongated spines of the anterior dorsal vertebrae, which support the hump, and in extreme shortness of the cannon bone, it is far from goat-like. The goat idea, indeed, has little more foundation than the suggestive resemblance of the profile with its caprine beard. It is truly no goat at all, and should more properly be regarded as an aberrant antelope, if anything could be justly termed "aberrant" in an aggregation of animals, hardly any two of which agree in all respects of structure. No American fossils seem to point to _Oreamnos_, and as _Nemorhaedus_ extends to j.a.pan and eastern Siberia, it is probable that it was an Asiatic immigrant, not earlier than the Pleistocene.
From this intricate genealogical tangle one turns with relief to the deer family, where the course of development lies reasonably plain. If the rank of animals in the aristocracy of nature were to be fixed by the remoteness of the period to which we know their ancestors, the deer would out-rank their bovine cousins by a full half of the Miocene period, and the study of fossils onward from this early beginning presents few clearer lines of evidence supporting modern theories respecting the development of species, than is shown in the increasing size and complexity of the antlers in succeeding geological ages, from the simple fork of the middle Miocene to those with three p.r.o.ngs of the late Miocene, the four-p.r.o.nged of the Pliocene, and finally to the many-branched shapes of the Pleistocene and the present age. Now it is further true that each one of these types is represented today in the mature antlers of existing deer, from the small South American species with a simple spike, up to the wapiti and red deer carrying six or eight points, and still more significant is it that the whole story is recapitulated in the growth of each individual of the higher races. The earliest cervine animals known seem to have had no antlers at all, a stage to which the fawn of the year corresponds; the subsequent normal addition in the life-history, of a tine for each year of growth until the mature antler is reached, answering with exactness to the stages of advance shown in the development-history of the race. A year of individual life is the symbol of a geological period of progression. This is a marvelous record, of which we may say--paraphrasing with Huxley the well-known saying of Voltaire--"if it had not already existed, evolution must have been invented to explain."
The least technical, and for the present purpose the most useful of the characters distinguis.h.i.+ng existing deer from all of the bovine stock, lies in the antlers, which are solid, of bony substance, and are annually shed. They are present in the males of all species except the Chinese water deer, and the very divergent musk-deer, which probably should not be regarded as a deer at all. They are normally absent from all females except those of the genus _Rangifer_. Most deer have canine teeth in the upper jaw, though they are absent in the moose, in the distinctively American type and a few others. The cleaned skull always shows a large vacuity in the outer wall in front of the orbit, which prevents the lachrymal bone from reaching the nasals. No deer has a gall bladder. There are many other distinctions, but as all have exceptions they are of value only in combinations.
The earliest known deer, belonging to the genus _Dremotherium_, or _Amphitragulus_, from the middle Tertiary of France, were of small size and had four toes, canine teeth and no antlers. Their successors seem to have borne simple forked antlers or horns, probably covered with hair, and permanently fixed on the skull. Very similar animals existed in contemporaneous and later deposits in North America. From this point the course of progress is tolerably clear as to deer in general, although we are not sure of all the intermediate details--for it must not be forgotten that a series of types exhibiting progressive modifications in each succeeding geological period is quite as conclusive in pointing out the genealogy of an existing group as if we knew each individual term in the ancestral series of each of its members. Thus we do not yet know whether the peculiar antler of the distinctively American deer, of the genus _Mazama_, is derived from an American source or took its origin in the old world, for the fossil antlers known as _Anoglochis_, from the Pliocene of Europe, are quite suggestive of the _Mazama_ style, but as nothing is known of the other skeletal details of _Anoglochis_, any such connection must at present be purely speculative, but the element of doubt in this special case in no way disturbs the certainty of the general conclusion that all our present _Cervidae_ have come through distinct stages in the successive periods, from the simple types of the middle Tertiary.
The family is undoubtedly of old world origin, and for the most part belongs to the northern hemisphere, South America being the only continental area in which they are found south of the equator.
The a.n.a.lytical habit of mind which finds vent in the subdivision of species, is also exhibited in a tendency to break up large genera into a number of small ones, but in the present group this practice has the disadvantage of obscuring a broad distinction between the dominant types inhabiting respectively the old world and the new. The former, represented by the genus _Cervus_, has a brow-tine to the antlers; has the posterior portion of the nasal chamber undivided by the vertical plate of the vomer; and the upper ends only of the lateral metacarpals remain, whereas in all these particulars the typical American deer are exactly opposite. As there are objections to considering these characters as of family value, arising from the intermediate position of the circ.u.mpolar genera _Alces_ and _Rangifer_, as well as the water deer and the roe, a broader meaning is given to cla.s.sification by retaining the comprehensive genera _Cervus_ and _Mazama_, and recognizing the subordinate divisions only as sub-genera.
The one representative of _Cervus_ inhabiting America is the wapiti, or "elk" (_C. canadensis_), which is without doubt an immigrant from Asia by way of Alaska, and it may be of interest to state the grounds upon which this conclusion rests, as they afford an excellent example of the way in which such results are reached. It is an accepted truth in geographical distribution, that the portion of the earth in which the greatest number of forms differentiated from one type are to be found, is almost always the region in which that type had its origin. Now, out of about a dozen species and sub-species of wapiti and red deer to which names have been given, not less than eight are Asiatic, so that Asia, and probably its central portion, is indicated as the region in which the elaphine deer arose; in confirmation of which is the further fact that the antler characteristic of these deer seems to have originated from the same ancestral form as that which produced the sikine and rusine types, which are also Asiatic. From this centre the elaphines spread westward and eastward, resulting in Europe in the red deer, which penetrated southward into north Africa at a time when there was a land connection across the Mediterranean. In the opposite direction, the nearer we get to Bering's Straits the closer is the resemblance to the American wapiti, until the splendid species from the Altai Mountains (_C. canadensis asiaticus_), and Luehdorf's deer (_C. c. luehdorfi_) from Manchuria, are regarded only as sub-species of the eastern American form, which they approach through _C. c.
occidentalis_ of Oregon and the northwestern Pacific Coast.
This evidence is conclusive in itself, and is further confirmed by the geological record, from which we know that the land connection between Alaska and Kamtschatka was of Pliocene age, while we have no knowledge of the wapiti in America until the succeeding period.
While there is not the least doubt that the smaller American deer had an origin identical with those of the old world, the exact point of their separation is not so clear. Two possibilities are open to choice: _Mazama_ may be supposed to have descended from the group to which _Blastomeryx_ belonged, this being a late Miocene genus from Nebraska, with cervine molars, but otherwise much like _Cosoryx,_ which we have seen to be a possible ancestor of the p.r.o.ng-horn; or we may prefer to believe that the differentiation took place earlier in Europe or Asia, from ancestors common to both. But there is a serious dilemma. If we choose the former view, we must conclude that the deciduous antler was independently developed in each of the two continents, and while it is quite probable that approximately similar structures have at times arisen independently, it is not easy to believe that an arrangement so minutely identical in form and function can have been twice evolved. On the second supposition, we have to face the fact that there is very little evidence from palaeontology of the former presence of the American type in Eurasia. But, on the whole, the latter hypothesis presents fewer difficulties and is probably the correct one; in which case two migrations must have taken place, an earlier one of the generalized type to which _Blastomeryx_ and _Cosoryx_ belonged, and a later one of the direct ancestor of _Mazama_. There is little difficulty in the a.s.sumption of these repeated migrations, for evidence exists that during a great part of the last half of the Tertiary this continent was connected by land to the northwest with Asia, and to the northeast, through Greenland and Iceland, with western Europe.
The distinction between the two groups is well marked. All the _Mazama_ type are without a true brow-tine to the antlers; the lower ends of the lateral metacarpals only remain; the vertical plate of the vomer extends downward and completely separates the hind part of the nasal chamber into two compartments; and with hardly an exception they have a large gland on the inside of the tarsus, or heel. The complete development of these characters is exhibited in northern species, and it has been beautifully shown that as we go southward there is a strong tendency to diminished size; toward smaller antlers and reduction in the number of tines; to smaller size, and finally complete loss of the metatarsal gland on the outside of the hind leg; and to the a.s.sumption of a uniform color throughout the year, instead of a seasonal change.
The two styles of antler which we recognize in the North American deer are too well known to require description. That characterizing the mule deer (_Mazama hemionus_) and the Columbia black-tailed deer (_M. columbiana_), seems never to have occurred in the east, nor south much beyond the Mexican border, and these deer have varied little except in size, although three subspecies have lately been set off from the mule deer in the extreme southwest.
The section represented by _M. virginiana,_ with antlers curving forward and tines projecting from its hinder border, takes practically the whole of America in its range, and under the law of variation which has been stated, has proved a veritable gold mine to the makers of names. At present it is utterly useless to attempt to determine which of the forms described will stand the scrutiny of the future, and no more will be attempted here than to state the present gross contents of cervine literature. The sub-genus _Dorcelaphus_ contains all the forms of the United States; of these, the deer belonging east of the Missouri River, those from the great plains to the Pacific, those along the Rio Grande in Texas and Mexico, those of Florida, and those again of Sonora, are each rated as sub-species of _virginiana_; to which we must add six more, ranging from Mexico to Bolivia. One full species, _M. truei,_ has been described from Central America, and another rather anomalous creature (_M. crookii_), resembling both white-tail and mule deer, from New Mexico.
The other sub-genera are _Blastoceros,_ with branched antlers and no metatarsal gland; _Xenelaphus,_ smaller in size, with small, simply forked antlers and no metatarsal gland; _Mazama_, containing the so-called brockets, very small, with minute spike antlers, lacking the metatarsal and sometimes the tarsal gland as well. The last three sub-genera are South American and do not enter the United States. Another genus, _Pudua_, from Chili, is much like the brockets, but has exceedingly short cannon bones, and some of the tarsal bones are united in a manner unlike other deer. In all, thirty specific and sub-specific names are now carried on the roll of _Mazama_ and its allies.
Attention has already been directed to the parallelism between the course of progress from simple to complex antlers in the development of the deer tribe, and the like progress in the growth of each individual, and to the further fact that all the stages are represented in the mature antlers of existing species. But a curious result follows from a study of the past distribution of deer in America. At a time when the branched stage had been already reached in North America, the isthmus of Panama was under water; deer were then absent from South America and the earliest forms found fossil there had antlers of the type of _M. virginiana_. The small species with simple antlers only made their appearance in later periods, and it follows that they are descended from those of complex type. This third parallel series, therefore, instead of being direct as are the other two, is reversed, and the degeneration of the antler, which we have seen taking place in the southern deer, has followed backward on the line of previous advance, or, in biological language, appears to be a true case of retrogressive evolution--representing the fossil series, as it were, in a mirror.
The reindeer-caribou type, of the genus _Rangifer,_ agrees with American deer in having the vertical plate of the vomer complete, and in having the lower ends of the lateral metacarpals remaining, but, like _Cervus,_ it has a brow-tine to the antlers. Of its early history we know nothing, for the only related forms which have yet come to light are of no great antiquity, being confined to the Pleistocene of Europe as far south as France, and are not distinguishable from existing species. Until recently it has been supposed that one species was found in northern Europe and Asia, and two others, a northern and a southern, in North America, but lately the last two have been subdivided, and the present practice is to regard the Scandinavian reindeer (_Rangifer tarandus_) as the type, with eight or nine other species or sub-species, consisting of the two longest known American forms, the northern, or barren-ground caribou (_R. arcticus_); the southern, or woodland (_R. caribou_); the three inhabiting respectively Spitzbergen, Greenland and Newfoundland, and still more lately four more from British Columbia and Alaska. The differences between these are not very profound, but they seem on the whole to represent two types: the barren-ground, small of size, with long, slender antlers but little palmated; and the woodland, larger, with shorter and more ma.s.sive antlers, usually with broad palms. There is some reason to believe that both these types lived in Europe during the interglacial period, the first-named being probably the earlier and confined to western Europe, while the other extended into Asia. The present reindeer of Greenland and Spitzbergen seem to agree most closely with the barren-ground, while the southern forms are nearest to the woodland, and these are said to also resemble the reindeer of Siberia. It is, therefore, not an improbable conjecture that there were two migrations into America, one of the barren-ground type from western Europe, by way of the Spitzbergen land connection, and the other of the woodland, from Siberia, by way of Alaska.
Little more can be said, perhaps even less, of the other circ.u.mpolar genus, _Alces_, known in America as "moose," and across the Atlantic as "elk." It also is of mixed character in relation to the two great divisions we have had in mind, but in a different way from reindeer.
Like American deer it has the lower ends of the lateral metacarpals remaining, and the antlers are without a brow-tine, but like _Cervus_ it has an incomplete vomer, and unlike deer in general, the antlers are set laterally on the frontal bone, instead of more or less vertically, and the nasal bones are excessively short. The animal of northern Europe and Asia is usually considered to be distinct from the American, and lately the Alaskan moose has been christened _Alces gigas_, marked by greater size, relatively more ma.s.sive skull, and huge antlers. Of the antecedents of _Alces_, as in the case of the reindeer, we are ignorant. The earlier Pleistocene of Europe has yielded nearly related fossils,[2] and a peculiar and probably rather later form comes from New Jersey and Kentucky. This last in some respects suggests a resemblance to the wapiti, but it is unlikely that the similarity is more than superficial, and as moose not distinguishable from the existing species are found in the same formation, it is improbable that _Cervalces_ bore to _AIces_ anything more than a collateral relations.h.i.+p.
[Footnote 2: The huge fossil known as "Irish elk" is really a fallow deer and in no way nearly related to the moose.]
Even to an uncritical eye, the differences between ungulates and carnivores of to-day are many and obvious, but as we trace them back into the past we follow on converging lines, and in our search for the prototypes of the carnivora we are led to the _Creodonta_, contemporary with _Condylarthra_, which we have seen giving origin to hoofed beasts, but outlasting them into the succeeding age. These two groups of generalized mammals approached each other so nearly in structure, that it is even doubtful to which of them certain outlying fossils should be referred, and the a.s.sumption is quite justified that they had a common ancestor in the preceding period, of which no record is yet known.
The most evident points in which _Carnivora_ differ from _Ungulata_ are their possession of at least four and frequently five digits, which always bear claws and never hoofs; all but the sea otter have six small incisor teeth in each jaw; the canines are large; the molars never show flattened, curved crests after the ruminant pattern, but are more or less tubercular, and one tooth in the hinder part of each jaw becomes blade-like, for shearing off lumps of flesh. This tooth is called the sectorial, or carna.s.sial.
Existing carnivores are conveniently divided into three sections: _Arctoidea_--bears, racc.o.o.ns, otters, skunks, weasels, etc.; _Canoidea_--dogs, wolves and foxes; _Aeluroidea_--cats, civets, ichneumons and hyaenas.
It is highly probable that these three chief types have descended in as many distinct lines from the _Creodonta_, and that they were differentiated as early as the middle Eocene, but their exact degree of affinity is uncertain; bears and dogs are certainly closer together than either of them are to cats, and it is questionable if otters and weasels--the _Mustelidae_, as they are termed--and racc.o.o.ns are really near of kin to bears.
Seals are often regarded as belonging to this order, but their relation to the rest of the carnivores is very doubtful. Many of their characters are suggestive of _Arctoidea_, but it is an open question if their ancestors were bear or otter-like animals which took to an aquatic life, or whether they may not have had a long and independent descent. At all events, doubt is cast upon the proposition that they are descended from anything nearly like present land forms by the fact that seals of already high development are known as early as the later Miocene.
The difficulty so constantly met with in attempting to state concisely the details of cla.s.sification, is well shown in this order, for its subdivisions rest less upon a few well defined characters than upon complex a.s.sociations of a number of lesser and more obscure ones, a recapitulation of which would be tedious beyond the endurance of all but practiced anatomists. For the present purposes it must be enough to say that bears and dogs have forty-two teeth in the complete set, of which four on each side above and below are premolars, and two above, with three below, are molars, but these teeth in bears have flatter crowns and more rounded tubercles than those of dogs, and the sectorial teeth are much less blade-like, this style of tooth being better adapted to their omnivorous food habits. Bears, furthermore, have five digits on each foot and are plantigrade, while dogs have but four toes behind and are digitigrade. These differences are less marked in some of the smaller arctoids, which may have as few as thirty-two teeth, and come very near to dogs in the extent of the digital surface which rests upon the ground in walking.
In distinction from these, _Aeluroidea_ never have more than two true molars below, and the cusps of their teeth are much more sharply edged, reaching in the sectorials the extreme of scissor-like specialization. In all of them the claws are more or less retractile, and they walk on the ends of their fingers and toes.
Cats are distinguished from the remainder of this section by the shortness of the skull, and reduction of the teeth to thirty, there being but one true molar on each side, that of the upper jaw being so minute that it is probably getting ready to disappear.
Civets, genets, and ichneumons are small as compared with most cats; they are fairly well distinguished by skull and tooth characters; their claws are never fully retractile, and many have scent glands, as in the civets. No member of this family is American.
Hyaenas have the same dental formula as cats, but their teeth are enormously strong and ma.s.sive, in relation to their function of crus.h.i.+ng bone.
No carnivore has teeth so admirably adapted to a diet of flesh as the cat, and, in fact, it may be doubted if among all mammals, it has a superior in structural fitness to its life habits in general.
The _Felidae_ are an exceedingly uniform group, although they do present minor differences; thus, some species have the orbits completely encircled by bone, while in most of them these are more or less widely open behind; in some the first upper premolar is absent, and some have a round pupil, while in others it is elliptical or vertical, but if there is a key to the apparently promiscuous distribution of these variations, it has not yet been found, and no satisfactory sub-division of the genus has been made, beyond setting aside the hunting-leopard or cheetah as _Cynaelurus_, upon peculiarities of skull and teeth.
True cats of the genus _Felis_ were in existence before the close of the Miocene, and yet earlier related forms are known. Throughout the greater part of the Tertiary the remarkable type known as sabre-toothed cats were numerous and widely spread, and in South America they even lasted so far into the Pleistocene that it is probably true that they existed side by side with man. Some of them were as large as any existing cat and had upper canines six inches or more in length. Cats have no near relations upon the American continent, nor do they appear to have ever had many except the sabre-tooths. Of present species some fifty are known, inhabiting all of the greater geographical areas except Australia. They are tropical and heat loving, but the short-tailed lynxes are northern, while both the tiger and leopard in Asia, and puma in America, range into sub-arctic temperatures, and it is a curious anomaly that while Siberian tigers have gained the protection of a long, warm coat of hair, pumas from British America differ very little in this respect from those of warm regions.
No other cat has so extensive a range as _Felis concolor_ and its close allies, variously known as puma, cougar and mountain lion, which extends from the Atlantic to the Pacific, and from lat.i.tude fifty-five or sixty north, to the extreme southern end of the continent. As far as is known, it is a recent development, for no very similar remains appear previous to post-tertiary deposits.
Bears of the genus _Ursus_ are of no great antiquity in a geological sense, for we have no knowledge of them earlier than the Pliocene of Europe, and even later in America, but fossils becoming gradually less bear-like and approximating toward the early type from which dogs also probably sprung, go back to the early Tertiary creodonts.
Cats, as we have seen, are chiefly tropical, while bears, with two exceptions, are northern, one species inhabiting the Chilian Andes, while the brown bear of Europe extends into North Africa as far as the Atlas Mountains.
The family _Procyonidae_ contains the existing species which appear to be nearest of kin to bears. These are all small and consist of the well-known racc.o.o.n, the coatis, the ring-tailed ba.s.saris and the kinkajou, all differing from bears in varying details of tooth and other structures. The curious little panda (_Aelurus fulgens_) from the Himalayas, is very suggestive of racc.o.o.ns, and as forms belonging to this genus inhabited England in Pliocene times, it is possible that we have pointed out to us here the origin of this, at present, strictly American family; but, on the other hand, evidence is not wanting that they have always been native to the soil and came from a dog-like stock.
As we have already seen, bears have the same dental formula as dogs, but as they are less carnivorous, their grinders have flatter surfaces and the sectorials are less sharp; in fact they have very little of the true sectorial character. It is unusual to find a full set of teeth in adult bears, as some of the premolars invariably drop out.
It is fully as true of bears as of any other group of large mammals, that our views as to specific distinction are based upon data at present utterly inadequate, for all the zoological museums of the world do not contain sufficient material for exhaustive study and comparison. The present writer has examined many of these collections and has no hesitation in admitting that his ideas upon the subject are much less definite than they were ten years ago. It does appear, though, that in North America four quite distinct types can be made out. First of these is the circ.u.mpolar species, _Ursus maritimus_, the white or polar bear, which most of us grew up to regard as the very incarnation of tenacious ferocity, but which, as it appears from the recitals of late Arctic explorers, dies easily to a single shot, and does not seem to afford much better sport than so much rabbit shooting.
The others are the great Kadiak bear (_U. middendorfi_); the grizzly (_U. horribilis_), and the black or true American bear (_U. america.n.u.s_). The extent to which the last three may be subdivided remains uncertain, but the barren-ground bear (_U. richardsoni_) is surely a valid species of the grizzly type.
The grizzlies and the big Alaska bears approach more nearly than _america.n.u.s_ to the widespread brown bear (_U. arctos_) of Europe and Asia, and the hypothesis is reasonable that they originated from that form or its immediate ancestors, in which case we have the interesting series of parallel modifications exhibited in the two continents, for the large bear of Kamtschatka approaches very nearly to those of Alaska, while further to the south in America, where the conditions of life more nearly resemble those surrounding _arctos_, these bears have in the grizzlies retained more of their original form.
Whether or not the large Pleistocene cave bear (_U. spelaeus_) was a lineal ancestor is questionable, for in its later period, at least, it was contemporary with the existing European species. The black bear, with its litter-brother of brown color, seems to be a genuine product of the new world.
Many differential characters have been pointed out in the skulls and teeth of bears, and to a less extent, in the claws; but while these undoubtedly exist, the conclusions to be drawn from them are uncertain, for the skulls of bears change greatly with age, and the constancy of these variations, with the values which they should hold in cla.s.sification, we do not yet know.
It is not improbable that the reader may leave this brief survey with the feeling that its admissions of ignorance exceed its affirmations of certainty, and such is indeed the case, for the law of scientific validity forbids the statement as fact, of that concerning which the least element of doubt remains. But the real advance of zoological knowledge must not thereby be discredited, for it is due to those who have contributed to it to remember that little more than a generation ago these problems of life seemed wrapped in hopeless obscurity, and the methods of investigation which have led to practically all our present gains, were then but new born, and with every pa.s.sing year doubts are dispelled, and theories turned into truths. There was no break in physical evolution when mental processes began, nor will there be in the evolution of knowledge as long as they continue to exist.
_Arthur Erwin Brown_.
[Ill.u.s.tration: TROPHIES FROM ALASKA.]
Big Game Shooting in Alaska