463 



This series includes six teeth. The last molar (ib. ib. m 3) is represented by a partially 

 developed crown in its formative cell ; the next in advance (m 2) is not fully risen into 

 place, and the summits of its two lobes are unworn. The antepenultimate molar (m 1), 

 with these ridges just touched, shows on each a polished linear tract of enamel; the 

 three anterior teeth, with progressively increasing degrees of wear and decrease of size 

 as they precede in position, are therefore deciduous molars (d 4, d a, d 2). Of this phase 

 of dentition, as seen from the outer side view of the right ramus, a figure is given in 

 Plate XCV. fig. 6. 



The foremost tooth (d 2) shows a working-surface of a triangular form, the base turned 

 backward, the apex forward and obtuse. The outer border has a submedian notch 

 corresponding to a groove terminating there, which divides the outer surface into a fore 

 and hind lobe, both of which are convex transversely, and in a minor degree vertically. 

 The inner side of the tooth is flatter, and is impressed at its middle third by three shallow 

 parallel grooves descending rather obliquely backward. The coronal ends of these 

 grooves give a crenate character to that part of the enamel. A field of dentine is exposed 

 on the broader hind lobe. 



The crown of the second molar (Plates XCII. fig. 1 & XCV. figs. 6 & 7, d 3) has the 

 two transverse lobes and a prebasal production ; a continuous tract of dentine is exposed 

 on these parts and along the mid link connecting the two lobes. Certain longitudinal 

 impressions on the outer surface of the crown give a wavy character to parts of the 

 peripheral coat of enamel on the working-surface of the tooth. 



The third molar (d *) is mutilated by fracture in both rami, but least so in the right. 

 The prebasal ridge is narrow transversely in proportion to its length ; its enamel coat 

 is indented ; the fore limb is feebly indicated. The hind surface of the hind lobe shows 

 three vertical enamel-ridges, two of which attain the grinding-surface. The mid link 

 is strengthened by a vertical ridge on its inner side. 



In the fourth molar (m 1) the prebasal ridge has a distinct link passing from its outer 

 angle toward the middle of the fore part of the front lobe, ending nearer the outer side. 

 Short ridges project from this surface on the inner side, marked off by the fore link. 

 The mid link passes from near the outer side of the fore lobe to near the middle of the 

 hind lobe. The link is complicated by a vertical ridge or fold of enamel on its inner 

 surface. Similar ridges mark the inner half of the fore surface of the hind lobe. On 

 the hind surface of this lobe, internal to the ridge by which the outer convex end there 

 terminates, is a narrow pyramidal tract of enamel in low relief, the apex of which reaches 

 the working-ridge of that lobe ; internal to this pyramid is a second, less strongly defined 

 by two sharp linear grooves. The inner side or end of each transverse lobe is narrower. 



The fresh and unworn crown of the penultimate molar (m 2) shows well the accessory 

 ridges which complicate the enamel cap of its crown. In this tooth, as in m i, the pre- 

 basal ridge beginning near the base of the inner end of the fore lobe curves forward and 

 outward, rising rapidly to a narrow summit, which seems to represent a third short trans- 

 verse lobe ; this, as soon as it has received or sent off the fore link, subsides suddenly 

 upon the base of the fore lobe before attaining its outer end. 



