OF THE MESOZOIC MAMMALIA. 
211 
the same line and left a distinctly serrate, sutural edge. The two foremost teeth, it 
follows, are in the premaxilla, while the diastema and the seven teeth behind it are in 
the maxilla. The anterior border of the premaxilla is smooth and rounded, sloping 
obliquely backwards; the outer face bulges around the fang of the large vertical 
incisor. Above the diastema, the njaxilla is slightly concave, and then swells out 
into the widely arching zygomatic process; the infraorbital foramen is above the third 
premolar. 
The foremost incisor lacks the tip of the crown ; it is strongly convex and vertically 
placed, with a straight anterior edge and a small cusp upon the slightly oblique pos- 
terior cusp. The second incisor has a comparatively low, simple, pointed crown with 
anterior and posterior accessory cusps ; it apparently lacks the vertical surface grooves 
which are so conspicuous on the premolars. Behind the suture is a wide, smooth 
diastema with no apparent trace of an alveolus. The three teeth which follow are evi- 
dently premolars, as they are well distinguished from the remainder of the maxillary 
series. It is uncertain whether they possess 
one or tAvo fangs. The crowns are oval in sec- 
tion, wdth the short axis transverse; they are 
compressed towards the tip and bear three 
sub-equal cusps, equidistant, one anterior and 
two posterior. The posterior cusps are oppo- 
site, giving the tooth a bicuspid appearance in 
outer and inner view^ (Mes. Mamm., PL III, 
fig. 6B). There is an internal cingulum, but 
no external cingulum was observed. The 
sides of the crown are marked by grooves, maxilla of Bolodon, enlarged 4 diameters. 
Avhich converge at the summit. In both specimens the third premolar is slightly 
smaller than the first and second. The four molars have comparatively Ioav and elon- 
gate croAvns. There is a prominent cingulum upon the outer face, which partly embraces 
the anterior and posterior slopes of the croAvn. The croAvn supports a double longitu- 
dinal roAv of small cusps. In the outer row of the first, second and third molars there 
are three cusps ; in the fourth molar there are only tAvo outer cusps, which are some- 
what more prominent. In the inner roAv of the first, second and fourth molars there 
are three cusps, Avhile the third molar has four cusps in the inner row. Each of these 
cusps is a minute cone, Avith faintly grooved sides. In the third and fourth molars 
there is a Avell Avorn, longitudinal groove betAveen the inner and outer rows Avhich cuts 
into the inner slopes of the cusps. In the first and second molars, on the other hand, 
there is no trace of such a Avorn median groove, but the Avhole inner face of the tooth. 
Figure 5. The outer surface of the right 
1 Professor Owen was misled by this bicuspid appearance in a fragmentary specimen (fig. 6), and de- 
scribed the two premolars as molars. 
