DESCRIPTION OF PLATES. 81 
shows three molars and three premolars, with a portion of the canine. 
The condyle, coronoid process, and descending process are wanting. 
The lower margin is straight:—B.M. 
Figs. 5 and 5 a.—H. Sivalensis. Lower jaw, more perfect ; viewed 
from above and also laterally. The alveolar ridges on both sides are 
perfect, and comprise three molars and three premolars, and also the 
alveolus of a fourth premolar. Both canines are broken off; but the 
right one is tolerably perfect, and is seen to curve back slightly at its 
tip. The incisive ridge is perfect, but the teeth are wanting. The 
width across the muzzle from the outer side of one canine alveolus to 
that of the other is greater, and the width of the jaw over the penulti- 
mate false molar is less, than in H. amphibius. The condyle, coronoid 
process, and descending ramus are wanting. The lower margin is 
straight.—B.M. 
Figs. 6 and 6 a.—H. Sivalensis. Lower jaw, viewed from above and 
also laterally. The posterior molars on both sides are wanting; but 
the two anterior molars and three premolars, on either side, and the two 
canines and s7z incisors are present. The space between the anterior 
premolar and the canine is very contracted. The right canine is very 
perfect. The anterior angle of the jaw below the canines is more 
abrupt, and the depth of the body of the jaw more regular, than in H. 
amphibius. The coronoid process is present, but the condyle and 
descending portion are wanting. The coronoid process is not projected 
so much forward as in H. amphibius. 
Figs. 7 and 7 a.—H. Sivalensis. Fragment showing symphysis of 
lower jaw, with canines and incisors remarkably perfect. The hori- 
zontal direction of the szx incisors and the peculiar curve of the canines 
upwards and slightly backwards are well seen. The incisors are of nearly 
equal dimensions, and the two central ones are not larger, as in J. 
amphibius; they are cylindrical, and inclined outwards at an obtuse 
angle to the plane of the grinding surface; their ends are truncated. 
They are much larger than in the specimen shown in fig. 6, so that the 
animal was probably an adult male.—B.M. 
Fig. 8.—H. Sivalensis. Large descending process of ramus of lower 
jaw, detached. This remarkable appendage for the attachment of the 
masseter and temporal muscles, peculiar to the genus, is even more 
developed than in H. amphibius; it is less tapering and more deep and 
massive in its proportions; the posterior margin is more round, and 
the anterior, which in H. amphibius is curved and pointed forwards, is 
here blunt and unmarked by any peculiarity of form. ‘The process is 
inclined outwards, and its outer surface is as marked for the reception 
of muscles as in the living Hippopotamus.—B.M. 
Fig. 9.—H. Sivalensis. Another specimen of descending process of 
ramus of lower jaw. 
Fig. 10.—Anterior portion of palate, with s/x incisors, and with 
three premolars on right side, and two on left.— B.M. 
Figs. 11 and 11 a.—Anterior portion of palate with canine and twa 
premolars ; viewed from above, and also laterally.—B.M. 
