2 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 5, 



of a left ramus ; the slight inclination of the cusps of the teeth 

 (figs. 1, 3, & 4) towards the end A, might be deemed evidence of its 

 belonging to the right ramus : but neither this degree of inclination, 

 nor the position of the accessory cusp, fig. 3 a, are decisive of the 

 way in which the fore end of the fragment points * . Not more of 

 the matrix can be safely meddled with, on the small chance of more 

 evidence to this comparatively unimportant point being had ; and 

 I shall, therefore, proceed with the description of the fossil on the 

 assumption that the shallower end, a, is the front end, the deeper 

 one, B, the hind end of the fragment, and that it is part of the left 

 ramus of the m.andible. 



This ramus is unusually shallow, and broad or thick below, the 

 side passing by a strong convex curve into the lower part ; a very 

 narrow longitudinal ridge, continued after its subsidence by a few 

 fine lines, forms a tract which divides the lateral from the under 

 surface : elsewhere the bone is smooth, without conspicuous vascular 

 perforations. The depth or vertical diameter of the ramus is not 

 more than two lines. 



This portion of jaw contains three teeth, the middle one of which 

 is the least mutilated ; and by carefully removing the matrix which 

 partly covered its crown, I exposed the whole of its singularly mo- 

 dified grinding surface. The first of the three teeth (figs. 1 & 2, «) 

 appears to have been smaller than the others, but its crown has been 

 too much broken to show its original characters. The third tooth, 

 c, is less mutilated : it is of the same size and had the same structure 

 as the middle one, h. Of this, the most perfectly preserved of the 

 three, h, careful drawings have been made, magnified about 8 dia- 

 meters, figs. 3, 4 & 5. 



The crown of this tooth is of a quadrate form, 3 millimeters by 

 '^\ millimeters, of very little height, and supports six subequal cusps, 

 in three pairs, each pair being more closely connected in the antero- 

 posterior direction of the tooth than transversely. 



The outer side of the crown (fig. 3), supported by a narrow fang 

 which contracts as it sinks into the socket, shows two principal 

 cusps or cones, o, o', and a small (anterior) accessory basal cusp, a. 

 A small portion of the outer side of the anterior cone, o, has been 

 chipped off ; that of the second cone, o\ shows a well-marked con- 

 vexity. The hard and shining enamel which covers these parts of 

 the crown contrasts with the lighter cement that coats the root, 

 fig. 3, r. The two outer lobes or cones are subcompressed, and placed 

 obliquely on the crown, so that the hinder one, d (fig. 5), is a little 

 overlapped externally by the front one, o, the fore part of the base 

 of the hinder one being prolonged inwards on the inner side of the 

 base of the front cone. The two middle cones (fig. 5, h, i) are sub- 

 compressed laterally, with the fore part of their base a little broader 

 than the back part. The two inner cones, ^, ^3', have their inner 

 surface (fig. 4) convex, with their summits slightly inclined forwards : 

 a small portion of enamel has been chipped off the hinder lobe, p'. 



* Compare the tooth, m 2, fig. 2 {Hyopotamus), Plate VIII., ' Quart. Joum', 

 Geol. Soc' vol. iv. 1848. 



