70 



the crown is but little increased. The rhomboidal form prevails ; the upper angle 

 being in contact with the upper and anterior angle of the more quadrate crown 

 of the last and largest premolar, and the trenchant border slopes therefrom down- 

 ward and forward to that of p 2. The lower angle of the rhomboid is formed by the 

 smooth shining bulge of enamel above the fang, or the chief anterior fang. Above that 

 the surface expands and flattens, with the slightest degree of concavity lengthwise, and the 

 feeblest indication of a ridge along the hind border. Two, or at most three, oblique 

 ridges mark the trenchant summit of the crown, whence they run a short way downward 

 and forward. 



In the last premolar {p 4), with a slight increase of height of crown, the antero- 

 posterior diameter prevails without increase of thickness. The anterior root, above which is 

 the enamelled swelling, is more plainly a subordinate support, instead of being the chief or 

 the sole one. The outer surface of the crown rises more directly from the posterior insertion 

 as a flattened tract. A feeble vertical ridge holds the same distance from the anterior 

 thickened border of the crown as does that which, in the preceding premolar, marks the 

 posterior border. The flattened part of the crown behind the short vertical rising in p 4, 

 thus seems to be a superadded part of the tooth, and may indicate the tooth, so symbolised, 

 to be a carnassial true molar ; but the test of development cannot, with present evidence, be 

 applied. The oblique ridges, six or seven in number, continued downward and forward 

 from the serrations of the trenchant margin, are limited to the upper half of the crown. 

 The hind part is lower than the fore part ; the serrate border sloping from before down- 

 ward and backward; that border of the four closely contiguous premolars describes an 

 unbroken convex curve, like the edge of a circular saw. The four trenchant teeth con- 

 stitute two thirds of the molary series. 



The first tubercular molar (m 1) has an oblong crown, with the long diameter from 

 before backward. Its vertical diameter is less than half that of the fore part of the 

 antecedent tooth. The grinding surface (PI. IV, fig. 9 b, m \) is divided by an antero- 

 posterior depression into an outer and an inner division, the inner wall rising highest ; 

 this presents three obtuse cones, the foremost being smallest, and the other two further 

 apart. The outer division is cleft into three more equal, smaller, and lower tubercles. 

 Below these the outer surface of the crown is not impressed or indented, but presents a 

 smooth moderate convexity from before backward. The three pairs of peripheral tubercles 

 in this minute lower molar recall the character of those of Slcreognaihus (PI. I, fig. 29), 

 though the resemblance is not so close as to the lower molar (PI. I, figs. G-12) of Microlestes. 



The last molar (m 2) loses in antero-posterior and vertical extent ; its middle depressed 

 surface is broader, and is bounded by narrow ridge-like low walls of enamel, with feeble 

 indications of a tubercular character, the inner and fore angle being most elevated. In 

 both molars the height of the crown is inconsiderable compared with the other dimensions. 



The outer and fore root of the coronoid process projects external to the alveolus of the 

 last molar, and shows the fractured surface, and the most prominent part of the outer 



