The Cambridge Natural History Part 25

Of the true sheep, genus _Ovis_, there are a considerable number of species. The Sheep are to be distinguished from the Goats by their rather stouter build and by the absence of the beard in the male. The horns are developed in both s.e.xes, and are usually twisted and often of large size.

The Sheep are almost entirely Palaearctic and Nearctic. They only just get into the Oriental region. One of the finest species is the great Pamir Sheep, _O. poli_, whose length reaches 6 feet {322} 7 inches, and height 3 feet 10 inches. The horns of this fine Sheep may measure more than five feet round the curves. The Rocky Mountain Bighorn (_O. montana_) is a Sheep ranging along the Rockies as far south as New Mexico, and also to the far north; they are not confined to the chain of mountains mentioned, but occur also on the mountains of British Columbia down to those of California. The horns are not quite as large as those of the last species, but measurements give a length (along the curve) of 32 to 40 inches.

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FIG. 171.--Himalayan Burrhel Sheep. _Ovis burrhel._ 1/12. (From _Nature_.)

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FIG. 172.--Blanford's Sheep. _Ovis blanfordi._ 1/10. (From _Nature_.)

Just as the Goats are often limited to islands and small stretches of country, so are the Sheep. Thus Cyprus has a species, _O. ophion_, peculiar to itself. This, which is known as the Cyprus Mouflon, is limited to a range of mountains, the Troodos, in that island. In 1878 it was believed that the animal was nearly exterminated, a flock of twenty-five members alone surviving. They have, however, since increased. Confined {324} to the Thibetan plateau are _O. hodgsoni_ and _O. nahura_. Corsica has the Mouflon, _O. musimon_; and the Barbary Sheep or Arui, _O. tragelaphus_, is found only in Northern Africa. _Ovis burrhel_ and _O. blanfordi_ are Indian forms.

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FIG. 173.--Barbary Sheep. _Ovis tragelaphus._ 1/10.

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FIG. 174.--Thar. _Capra jemlaica._ 1/10. (From _Nature_.)

_Ovis nahura_ is chiefly responsible for the impossibility of strictly separating the Sheep and Goats. It has no suborbital glands or lachrymal fossae, which are as a rule present in the Sheep and absent from the Goats.

On the other hand interdigital glands are present, which is the case with Sheep. Its habits, too, are a blending of those of the Sheep and the Goat.

It lives largely on undulating ground like Sheep, and frequently lies down during the day on its feeding ground. On the other hand it is, like the Goats, a splendid climber.

The Goats, genus _Capra_, differ from the Sheep in their slighter build and in the fact that the horns are not spirally curved, but arched over the back. There is also the characteristic beard, {325} and the male is odorous. The true Goats are almost exclusively Palaearctic in range. They show the limited distribution of the Sheep, a distribution which follows from their mountain-loving habits.

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FIG. 175.--Sinaitic Ibex. _Capra sinaitica._ 1/10.

Thus we have the Spanish Ibex (_C. pyrenaica_), limited to the Pyrenees and other mountain ranges of the peninsula; _C. ibex_, the Steinbok of the Alps and the Tyrol; the Markhoor, _C. falconeri_, of certain mountain ranges of Afghanistan; the Caucasian, Sinaitic, and Cretan Ibexes, and the Thar.

_Capra aegagrus_, the Persian Wild Goat, ranges from the Caucasus to Sind.

It is this animal which produces the true "bezoar stone." The substance in question is a secretion apparently found in the stomach. It is still, according to Mr. Blanford, regarded as an antidote to poison in Persia.

Buffon called this Goat the "Pasan," which is evidently a corruption of the word bezoar. When the substance was in repute as a medicine of the "alexipharmic" kind, the supply naturally came up to the demand. Thus the bezoar stones of the Lama in South America gained repute, and there were "Oriental bezoar, cow {326} bezoar, hog bezoar, and monkey bezoar"! As concretions of one kind or another are not uncommon objects in the alimentary tract of mammals it was easy enough to obtain a fair amount of some substance which was sure to sell well. It is said that a stone weighing four ounces was once sold in this country (or at any rate in Europe) for 200.

"There can be no doubt," observes Mr. Blanford, "that _C. aegagrus_ is one of the species, and probably the princ.i.p.al, from which tame goats are derived."

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FIG. 176.--j.a.panese Goat Antelope. _Nemorrhaedus crispus._ 1/12. (From _Nature_.)

The Chamois (_Rupricapra_) and the Goral (_Nemorrhaedus_) are best described as Goat-like Antelopes; but, as already said, it is difficult to split up the Bovidae satisfactorily. The Rocky Mountain Goat, _Haploceros monta.n.u.s_, is a large Goat-like creature, {327} which has the peculiarity of having the shortest cannon bones of any Ruminant. Its name denotes its range.

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FIG. 177.--Goral. _Nemorrhaedus goral._ 1/12. (From _Nature_.)

The Musk Ox, _Ovibos moschatus_, has been thought to be on the borderland between the Sheep and Oxen, as indeed expressed in its scientific name. It is a purely Arctic creature, now confined to the Nearctic region; but it formerly existed in the Arctic regions of Europe.

The anatomy of the "soft parts" of this genus has lately been investigated by Dr. Lonnberg.[218] The animal has no foot glands such as occur in _Ovis_. Its kidneys, however, are non-lobate, and it has...o...b..tal glands.

The cotyledons of the placenta are unusually large, and the cow has the "primary four" teats. It cannot, in fact, be definitely referred to either the Caprine or the Bovine section of the Cavicornia, and while possibly most allied to _Budorcas_, it may be regarded, at least for the present, as ent.i.tled to form a separate sub-family of its own. The muzzle {328} has a slight naked strip above the nostrils, as in the Sheep, but there is no fissure of the upper lip.

EXTINCT FAMILIES OF ARTIODACTYLA.

The origin of the Artiodactyla is placed by Cope in the family PANTOLESTIDAE,[219] allied to the genus _Protogonodon_ of the Condylarthra.

As, however, this family is represented by but a few back teeth and a fragment of the hind-foot, it seems premature to regard it as the necessary starting-point of the Bunodont and Ruminant groups.

FAM. ANTHRACOTHERIIDAE.--This well-known and ancient family consists of creatures of for the most part a Pig-like form, with teeth approaching the selenodont shape, and a complete dent.i.tion. The carpals, tarsals, metacarpals, and metatarsals are all free. The toes are four (or five) to each foot, with the outermost beginning to be reduced. These of course are all generalised and primitive characters, pointing nowhere in particular, except, of course, to an Artiodactyle stock, on account of the teeth and the two predominating toes.

The type genus of the family, _Anthracotherium_, is not, as its name might seem to denote, a relic of the Carboniferous period; its remains were found in lignite, which may also show that it was at least semi-aquatic in habit.

Its form, however, must have been Pig-like, so at least one would presume from the elongated skull and shortish legs. There were species as great as a Rhinoceros, and smaller forms. The genus began in the Oligocene and continued down to the Pliocene. It is known from Europe, Asia, and America.

The skull is long with a prominent sagittal crest. The facial part is also very long, and the orbits are not closed by a bony ring. The premolars are simple teeth; the molars distinctly bunodont with a tendency in one or two to the selenodont condition. The canines are powerful, as are also the incisors. The scapula has been specially compared with that of the Camel.

It has no acromion, which is usually though not always absent in Ungulates.

An ally of the present animal, for instance, the Hippopotamus, has the acromion developed. The radius and ulna, the tibia and fibula, are all fully developed. {329}

_Ancodus_ (or _Hyopotamus_, as it has been called) is also Oligocene in range, and its remains have been found in the same countries as have those of _Anthracotherium_. Both genera are indeed closely allied. _Ancodus_ seems to be a more slightly-built creature. The skull looks weaker, but presents much the same features of organisation. In _A. velaunus_, a species found in French rocks, a metacarpal of digit I. was present in the ma.n.u.s, while _A. brachyrhynchus_ had a completely five-fingered ma.n.u.s.

The Miocene genus _Merycopotamus_ (from the lower layers of the Siwalik formation in India) is more distinctly selenodont than the forms already discussed. On this ground it has been placed in a separate sub-family. As, however, in other respects it does not depart from the Anthracotherian type of structure, this proceeding seems to be hardly necessary. There are two species known, of which one, _M. na.n.u.s_, is, as its name denotes, a dwarf form.

FAM. CAENOTHERIIDAE.--While the last family consisted of animals rather more akin to the Pigs, the present is more Pecorine in its characters. The molars are selenodont; but as in the Tragulidae the premolars are more of the nature of cutting teeth. The dent.i.tion, like that of so many of these early Ungulates, is complete, and the canines are not prominent. The feet are four-toed, the lateral toes not reaching the ground.

The princ.i.p.al genus is the Eocene and Miocene _Caenotherium_. Of this genus there were a considerable number of species all European in range, and of small size--not more than a foot or so in length. Their small size is suggestive of the Chevrotains. In the skull the orbital cavity is nearly or quite surrounded by bone, and the tympanic bulla is large and inflated. A common feature of Artiodactyles, a failure of the nasals and maxillae to meet at the side of the face, is to be seen in this ancient forerunner of the Pecora.

_Plesiomeryx_, also European, and from the same geological horizon, is a very closely allied form.

FAM. XIPHODONTIDAE.--This family consists of slender, small Artiodactyles which are, like the Caenotheriidae, related to the Pecora. They are confined in their range to Europe.

The type genus _Xiphodon_ has selenodont molars and elongated, slender, cutting premolars. The dent.i.tion was complete and the canines not highly developed. Like _Caenotherium_, {330} _Xiphodon_ was a hornless creature, but with only two toes, the two lateral digits being represented by the merest rudiments of metacarpals. The other metacarpals were unusually long.

_Amphimeryx_ (also called _Xiphodontotherium_) is much more imperfectly known, but belongs to this family or to that of the Caenotheriidae.

_Dichodon_ is another member of the same family.

FAM. OREODONTIDAE.--This family, consisting of numerous genera, is limited to the North American continent. Its range in time is from the Eocene to the Lower Pliocene. The family as a whole is to be distinguished by a number of primitive characters. The dent.i.tion is complete; the feet are four- or even five-toed; the orbit is sometimes open behind. The canines of the lower jaw are not more p.r.o.nounced than the incisors. The characteristics of the group will be further developed by a consideration of some of the princ.i.p.al genera which are included in this family.

_Oreodon_ is a Miocene form about as large as a Peccary. The skull has a short face with a completely-closed orbital cavity. In front of the orbit is a deep pit, not a mere deficiency of ossification, such as occurs in many Artiodactyles. This is placed on the lachrymal bone, and is in fact a lachrymal fossa, such as occurs in other forms. The odontoid process of the axis vertebra is somewhat cheese-taster shaped, as in recent Artiodactyles.

There are fourteen dorsal vertebrae and a very large number of caudals. The radius and the ulna are completely separated, as are the carpals. There are five digits to the fore-limbs. The fibula is complete and independent. The hind-foot is four-toed. Several species of the genus are known.

_Merycoch.o.e.rus_ is an allied Miocene genus. It is more ma.s.sive in form than the last, but otherwise does not present differences of importance.

_Mesoreodon_ is another genus of this family which presents some curious features of organisation. In the skull and teeth there is nothing very noteworthy, but the hyoid is remarkable. This appendage of the skull is by no means always preserved, and when it is, it might be denied that it belonged to any particular skull. In the present case there appears to be no doubt as to the ident.i.ty of the bones, which resemble the corresponding bones of the Perissodactyla much more than they do those of other Artiodactyles. a.s.sociated with the bones an ossified {331} thyroid cartilage of the larynx was found. As the skull was that of a male, this character may be a s.e.xual one. It is quite comparable to the ossification of the same cartilage in the American monkey _Callithrix_. "The function of the bone," observes Professor Scott,[220] "was probably similar to that performed by the enormously-inflated basihyal of the howling monkeys, and must have given to these animals most unusual powers of voice." Another important anatomical fact about _Mesoreodon_ is the apparent existence of a clavicle. It is of course conceivable that the remains of some other animal have got mixed up with that of the individuals upon which the present genus is founded; but failing that, here is a clavicle in an Ungulate. The spine of the scapula possesses a metacromion. This greater development of the spine of the scapula in Artiodactyles than in Perissodactyles is, it is suggested, to be correlated with the earlier loss of the clavicle in the latter group of Ungulates.

_Cyclopidius_ (synonymous with _Brachymeryx_) is a kind of pug form of _Oreodon_. The skull is short and broad, and the end of the snout a little turned up. The upper incisors are small and drop out early. On each side of the nasals is a large oval vacuity which is perhaps to be compared to the lateral deficiency to be found in other Artiodactyles. One species of this singular-looking form is appropriately called _C. simus_.

Other allied genera are _Merychyus_ and _Leptauchenia_. The former extends as far down as the Lower Pliocene, and is thus one of the newest forms of Oreodontidae.

_Agrioch.o.e.rus_[221] (Fig. 178) is placed in a separate sub-family from the types which have just been considered. It is Miocene in range. It differs from _Oreodon_ and its closer relatives by the fact that the orbit is open behind and not closed. The most remarkable fact about this creature is that the terminal phalanges of the digits (five in the fore- and four in the hind-feet) being pointed, seem to suggest their encas.e.m.e.nt with claws rather than hoofs. The pollex, though small, seems to have been opposable.