which are harder
than the other parts, almost like the plates on the Indian rhinoceros, hang
about the shoulders and rump. It is coloured black, with white feet, and
breeds true. That it has long been domesticated there can be little doubt;
and this might have been inferred even from the fact that its young are not
longitudinally striped; for this is a character common to all the species
included within the genus _Sus_ and the allied genera whilst in their
natural state.[154] Dr. Gray[155] has described the skull of this animal,
which he ranks not only as a distinct species, but places it in a distinct
section of the genus. Nathusius, however, after his careful study of the
whole group, states positively (Schweineschaedel, s. 153-158) that the skull
in all essential characters closely resembles that of the short-eared
Chinese breed of the _S. Indica_ type. Hence Nathusius considers the Japan
pig as only a domesticated variety of _S. Indica_: if this really be the
case, it is a wonderful instance of the amount of modification which can be
effected under domestication.

[Illustration: Fig. 2.--Head of Japan or Masked Pig. (Copied from Mr.
Bartlett's paper in Proc. Zoolog. Soc. 1861, p. 263.)]

Formerly there existed in the central islands of the Pacific Ocean a
singular breed of pigs. These are described by the Rev. D. Tyerman and G.
Bennett[156] as of small size, hump-backed, with a disproportionately long
head, with short ears turned backwards, with a bushy tail not more than two
inches in length, placed as if it grew from the back. Within half a century
after the introduction into these islands of European and Chinese pigs, the
native breed, according to the above authors, became almost completely lost
by being repeatedly crossed with them. Secluded islands, as might have been
expected, seem favourable for the production or retention of peculiar
breeds; thus, in the Orkney Islands, the hogs have been described as very
small, with erect and sharp ears, and "with an appearance altogether
different from the hogs brought from the south."[157]

Seeing how different the Chinese pigs, belonging to the _Sus Indica_ type,
are in their osteological characters and in external {71} appearance from
the pigs of the _S. scrofa_ type, so that they must be considered
specifically distinct, it is a fact well deserving attention, that Chinese
and common pigs have been repeatedly crossed in various manners, with
unimpaired fertility. On