National Institute of Informatics - Digital Silk Road Project
Digital Archive of Toyo Bunko Rare Books

Siberia, from the Warwarinskischen "Yourts," on the River Tobol, and with the
djiggetai (Equus hemionus). We must, therefore, first settle the question whether
these cranial remains really belong to a horse or to a half-ass, like the djiggetai,
or to a kiang.

Investigation into the relation of the teeth of the horse to those of the djiggetai
and ass has been carried out most thoroughly by L. Rütimeyer,* R. Owen,†
J. C. Forsyth Major,‡ A. Nehring,§ T. Frank,‖ and M. Wilckens.¶

In consequence of these studies the following distinctive characteristics
between the Western and the Oriental horse groups and the asses are available.

ORIENTAL HORSE GROUP (BROAD-FRONTED HORSES).

The premolars of the upper and lower jaws have a larger or equally large
transverse diameter of the grinding surface with the longitudinal diameter. The
plications of the enamel pattern are here considerably smaller than in western
horses and the interior pillars of the anterior island appear rounded.

OCCIDENTAL HORSE GROUP (NARROW-FRONTED HORSES).

The premolars are here more drawn out in the length; hence the depth of the
grinding surface is greater than in the transverse diameter. The enamel plications
of the islands are considerably more folded, and the ant-external horn of the pos-
terior island surpasses the post-external horn of the anterior island, projecting
further outward, even on the molars, on which in oriental horses they stand almost
even. In the same way the stronger plication of the enamel margin on the internal
lobe causes in the Occidental horse the striking bifurcation of the internal lobule
and the stronger development of the spur** in the ant-oblique valley.

ASSES AND HALF-ASSES.

In the asses and half-asses the longitudinal diameter of the crown is still
shorter in comparison with the transverse diameter than in the oriental horse,
the enamel plications are less prominent, and the spur is wholly wanting in the
ant-oblique valley.

Tscherski†† gives a method by which he says the relationship to one of the
groups mentioned can be expressed in figures. This is the determination of the
index of projection of the anterior lobule of the interior pillar. If we take the
distance from the posterior margin of the crown to the next point of the bottom