The corresponding teeth in all the South African species agree in very many points, and thus
the general resemblance may be said to be very strong. Minute examinations, however,
divulge many well-marked differences which are more easily perceived than described. Each
jaw contains twenty teeth, ten on each side. In the upper jaw, the series of one. side is
separated from that of the other at the anterior point of the intermaxillary bone ; in the lower
jaw no division exists, the two anteriormost teeth being in juxta-position. For the sake of
convenience, we may consider the teeth of each jaw under three divisions, viz. incisors, false
molars, and true molars. The incisors are six in number, and in the upper jaw are lodged in
the intermaxillary bones ; the false molars are two on each side ; the remainder are classed as
true molars. In M. typicus the teeth of each side are continuous, but in the other species
several of the anterior ones are more or less apart from each other. With respect to form, the
incisors o f the upper jaw differ but little from each other, they are all laterally compressed,
the inner surface of each is distinctly concave, and the outer slightly convex, the two anterior-
most ones are slightly longer than the other four, and all have an oblique cutting edge, the
most projecting point o f which is at the front of each tooth. The false molars are very short,
compressed, and slightly bicuspidate, the one point immediately behind the other. The true
molars are quadricuspidate, two points on the outer edge and two on the inner, but the latter
never reach the level of the former; hence the crown of each tooth exhibits an inward slope;
in the hindermost molar the two posterior points are always but imperfectly developed. The
incisors of the under jaw are more compressed than those of the upper; the two false molars
resemble closely those' of the upper jaw, the first and second true molars have more the
appearance of false than true ones ; indeed, they might with more propriety be ranked with
the former than the latter; they are strongly compressed and faintly tricuspidafe, the points
being disposed in a longitudinal line : the three hindermost molars are quadricuspidate, and
the external and internal points attain the same level.
The following are the parts represented—
1 a The upper surface of the skull of M. typicus of the natural size.
1 b The lateral parts of do. do. . do.
1 c The lower jaw of . do. . . do.
1 d The under surface of the skull of do. of double the natural size.
1 e The lower jaw of . do. . do.
1 ƒ The stomach of . . do.
1 g The caecum of do., together with a portion of the large and small intestines.
1 k The liver of do., consisting of four very unequal-sized lobes.
1 i The left kidney of do.
2 a The upper surface of the skull of M. rupestris, o f the natural size.
2 b The lateral parts of do. do. do.
2 c The lower jaw of do. do.
3 a The upper surface of the skull of M. intufi. do.
3 b The lateral parts of do. do. do.
3 c The lower j aw of do. do.
4 a The upper surface of the skull of M. brachyrynchus. do.
4 b The lateral parts of do. do. do.
4 c The lower jaw 0f do. do.