Page:Encyclopædia Britannica, Ninth Edition, v. 22.djvu/805

 Incisors rooted. Upper canines curving more or less outwards or upwards. Stomach simple, except for a more or less de- veloped pouch near the cardiac orifice. A csecum. Colon spirally coiled. Confined to the Old World. Sus. Dentition : "t f, c |, p , _ m ; total 44. Upper incisors diminishing rapidly in size from the first to the third. Lower incisors long, narrow, closely approximated, and almost horizontal in posi- tion, their apices inclining towards the middle line ; the second slightly larger than the first, the third much smaller. Fio. 1. Dentition of Boar (Sus scrofa}. Canines strongly developed and with persistent roots and partial enamel covering, those of the upper jaw not having the usual downward direction, but curving strongly out- wards, up wards, and finally inwards, while those of the lower jaw are directed upwards and outwards with a gentle back- ward curve, their hinder edges working and wearing against the front edges of the upper canines. 1 They appear ex- ternally to the mouth as tusks, the form of the upper lip being modified to allow of their protrusion, but are much less developed in the females than in the males. The teeth of the molar series gradually increase in size and complexity from first to last, and are arranged in con- tiguous series, except that the first lower premolar is separated by an interval from the second. First and second upper premolars with compressed crowns and two roots. The third and fourth have an inner lobe developed on the crown, and an additional pair of roots. The first and second true molars have quadrate crowns, with four principal obtuse conical cusps, around which numerous accessory cusps are clustered. The crown of the third molar is nearly as long (antero-posteriorly) as those of the first and second together, having, in addition to the four principal lobes, a large posterior talon or heel, composed of numerous clustered conical cusps, and supported by several additional roots. The lower molar teeth resemble generally those of the upper jaw, but are narrower.' 'Milk dentition: if, ci, wf; total 28, the first permanent premolar having no predecessor in this series. The third incisor, in both upper and lower jaw, is large, developed before' the others, and has much the size, form, and direction of the canine. Vertebra : C 7, D 13-14, L 6, S 4, C 20-24. The hairy covering of the body varies much under different conditions of climate, but when best developed, as in the European wild boar, consists of long stiff bristles, mostly abundant on the back and sides, and of a close softer curling under-coat. 1 If from any accidental circumstances these teeth are not con- stantly worn down by friction, they grow into a complete circle, the point penetrating the bone of the jaw close to the root of ; the tooth. The natives of the Fiji Islands avail themselves of this circumstance to produce one of their most valued ornaments a circular boar's tusk : the upper canines being extracted, the lower ones are allowed to grow to the desired form. 773 This genus occurs at present under three principal modifications or subgenera. A. Sus proper comprises a number of animals found in a wild state throughout the greater part of Europe (except where exterminated by human agency), the north of Africa, southern continental Asia, and the great islands of the Malayan archipelago, Formosa, and Japan. The following among others have been admitted by zoologists as distinct species : Sus scrofa, the wild boar of Europe, Asia Minor, and North Africa, once common throughout the British Isles; S. sennaarensis, North-East Africa; S. cristatus, Hin- dustan; S. vittatus, Java, Borneo, Amboyna, Batchian; S. barbatus, Borneo; S. papuensis, New Guinea; S. timorensis, Timor and Rotti ; S. andamanensis, Andaman Islands ; S. celebensis, Celebes ; S. taivanus, Formosa ; S. leucomystax, Japan ; S. verrucosus, Java, Borneo, Ceram. This list will give some idea of the geographical distribution of wild pigs, but it must be borne in mind that through the whole of this region, and in fact now throughout the greater part of the habitable world, pigs are kept by man in a domesticated state, and it is still an open question whether some of the wild pigs of the islands named above may not be local races derived originally from imported domestic specimens. In New Zealand a wild or rather " feral "' race is' already established, the origin of which is of course quite recent, as it is well ascertained that no animal of the kind ever lived upon the island until after its settlement by Europeans. Whether the various breeds of domestic pigs have been derived from one or several sources is still unknown. As in so many similar cases there is no historic evidence upon the subject, and the researches of naturalists, as Nathusius, Eutimeyer, Ilolleston, and others, who have endeavoured to settle the question on anatomical evidence, have not led to satisfactory con- clusions. It is, however, tolerably certain that all the species or forms of wild pigs enumerated above and all the domestic races are closely allied, and it is probable (though of this there has been no opportunity of proof) FIG. 2. Wild Boar and Young. will breed freely together. It is a curious circumstance that the young of all the wild kinds of pigs (as far as is known at present) present a uniform coloration, being dark brown with longitudinal stripes of a paler colour, a character which completely disappears after the first few months. On the other hand, this peculiar marking is rarely seen in domestic pigs in any part of the world, although it has been occasionally observed. It is stated by Darwin that the pigs which have run wild in .Jamaica