part 4 .] LgdeMer: Osteology of Merycgpotamus dlssimilis. 
145 
Cranium. —My examination of the cranium lias been chiefly confined to the young 
specimen from Burma noticed above, which from the state of the sutures is in a very 
favourable state for comparison. The general form of the skull somewhat resembles that of 
Hippopotamus, especially in the long even slope from the occipital crest to the extremity of 
the nasals, and in the comparatively slight depth of the upper portion of the cranium ; the 
wide zygometic arches and the deep and sharp sagittal crest are also Hippopotamine 
characters. The muzzle is slightly expanded at its extremity, but not to the same enormous 
extent as in Hippopotamus. 
Orbits .—The orbits are approximately circular, and completely surrounded by a bony 
ring; their superior borders arc somewhat produced and elevated, forming the highest points 
on the forehead, while the frontals are considerably depressed below them ; in all the above 
characters the skull of Merycopotamus agrees closely with that of Hippopotamus, and 
differs from that of Sits. The orbit is placed unusually far forwards, so that its inferior 
border is directly over the hinder barrel of the first molar : the distal articulation of the 
jugal reaches as far forwards as the first premolar. In Hippopotamus the inferior border 
of the orbit is placed over the binder barrel of the second molar, and in Sits over the middle 
of the last molar. 
Nasals .—The proximal extremity of the nasals does not extend upwards to within half- 
an-inch of the inferior border of the orbit; in this respect the skull more resembles that of 
Sus, since in Hippopotamus the proximal extremity of the nasals extends upwards beyond 
the centre of the orbits. The distal extremity of the nasals differs from that of both 
Hippopotamus and Sits; in Merycopotamus the nasals diminish in width very gradually 
from above downwards, and terminate somewhat above the extremity of the muzzle; their 
distal extremity is cut. into hv an acute re-euteriug angle; in Hippopotamus the nasals 
narrow very rapidly and terminate directly over the muzzle with a considerable expansion ; 
in Sus the nasals narrow gradually and terminate slightly above the muzzle in a pointed 
extremity. The facial surfaces of the nasals are nearly flat, and placed at right angles to 
the lateral surfaces of the maxilla), as in Sus; the nasals of Hippopotamus are rounded 
transversely on the facial surface, and do not form any marked angle at their junction with 
the maxilla). The greater portion of the outer border of the nasals articulates with the 
maxilla, and only a very small moiety with the premaxilla ; this character forms a marked 
distinction from Sus, and agrees with Hippopotamus, only in the latter a rather longer pro¬ 
portion of the nasals articulates with the premaxilla than in Merycopotamus ; the extremely 
small proportion of the premaxilla which articulates with the nasals in the latter genus is 
owing to the relative shortness of the latter bones. Tlio naso-maxillary suture is nearly 
straight, and thereby different from the same suture in both the allied genera; no portion of 
the premaxilla overlaps the facial surface of the nasals, as occurs in Sus, as distinguished 
from Hippopotamus. 
Maxilla and Jugal. —The lateral surface of the maxilla is somewhat hollowed; the 
foramen for the fifth nerve is placed directly over the last premolar, as in Sits; it is situated 
more anteriorly in Hippopotamus. The outer surfaces of the molar teeth are placed so far 
apart, that the jugal for a long distance along its posterior border becomes continuous with 
the lateral surface of the maxilla, aud does not overhang the latter as is the case in Hippo¬ 
potamus and Sus. There is no distinct process of the maxilla for articulation witli the jugal, 
on account of the junction of nearly the whole of the posterior surface of the latter with the 
maxilla; the form of this portion of the skull is quite peculiar to Merycopotamus ; the form 
of the union between the squamosal aud jugal is not known. 
Lachrymal. —The facial portion of the lachrymal is oblong in shape, and its surface is 
quite plane ; it is considerably elongated antero-postoriorly, so that it articulates with four 
