MCEEITHEEIUM. 109 



end the superior border runs upwards and backwards at right angles to it, so 

 that the very short coronoid process (cor.) does not rise above the articulation. The 

 condyle itself [cond.) is elongated from within outwards and short from before 

 backwards ; it is convex in both directions and is wider on the outer than on the 

 inner side, which is supported on a flange or buttress of bone arising from the inner 

 face of the ascending ramus. From the condyle the posterior border runs down- 

 wards and backwards in a wide sweeping curve, forming the broadly rounded 

 angular region which projects somewhat below the ventral border of the horizontal 

 ramus. The outer face of the ascending ramus between the thickened anterior 

 border and the buttress which bears the condyle is deeply concave, the bone being 

 very thin. 



Lower Dentition. — There are two pairs of incisors (PI. X. figs. 1, 1 A, i. 1, i, 2). 

 These teeth are procumbent and directed forwards, their upper surface forming a 

 continuation of the spout-like upper face of the symphysial region of the mandible. 

 The first incisors are much the smaller, and are closely crowded together between 

 the second pair. They seem to have been prismatic teeth with very long crowns and 

 roots ; their transverse width would be about 2'5 cm. The second incisors are a pair 

 of large tusks, which seem to have been more or less triangular in section near the 

 top of the crown, but ovate further down. No well-preserved examples have been 

 found in situ in the jaw, but two specimens which may be regarded as these teeth 

 are here noticed. One of them is a young tooth in which wear has just commenced ; 

 the upper face of its crown is concave from side to side, the inner face flat, while the 

 ventral face is convex and meets the upper face externally in an angle forming the 

 sharp outer edge of the crown, which is chisel-shaped, but thicker internally than at 

 its outer side. The wear-surface is nearly at right angles to the long axis of the 

 tooth ; it is narrow, but as wear proceeded would increase in depth till towards the 

 base of the crown it would be such as is found in the second older tooth referred to 

 below. The crown is covered with enamel, of which the surface is finely sculptured 

 with vermiculate markings below and irregular longitudinal ridges above. The 

 enamel extends much further dowti the upper and lower faces of the crown than on 

 the sides. In the older tooth the wear-surface is broad, flat, and oval in outline ; it 

 is slightly inclined to the long axis of the tooth, and on the inner and outer sides 

 has already passed below the level of the enamel-covered surface, so that the enamel 

 forms two separate bands, one on the upper, the other on the lower face. The root 

 is vei-y long and slightly curved, with a longitudinal groove on the concave side. At 

 this stage, at any rate, the root was closed. 



The third incisor, canine, and first premolar are wanting in the mandible. 



The anterior premolar (PI. IX. figs. 3, 3 a, pm. 2) is comparatively small, and narrow 

 from side to side. It consists of a large main cusp, in front of which there is a small 

 tubercle which may belong to the cingulum. Behind there is a large talon rising in 



