84 FOSSIL MAMMALIA OF THE 



The enamel of the apical half of the crown of the incisor, here preserved, shows a 

 fine longitudinally wrinkled character. The section or fracture of the crown indicates its 

 inner side to have had a sliallow longitudinal groove. The basal part of the crown has left 

 a partial impression indicating the diastema between it and the premolars not to have 

 been so long as at first sight appears. 



Part of the root of the small anterior premolar {p 2) is preserved. The penultimate 

 premolar {p 3) shows the usual four oblique ridges on the upper part of the crown. Six 

 ridges are discernible on the corresponding part of that of the broader last premolar (jo 4). 

 The width of the interspace of the two diverging roots of this tooth, and the transverse 

 breadth of the base of the crown, are well shown in this specimen. It has belonged to an 

 animal quite as large as the type of Plagiaulax Becklesii, and it most probably belongs to 

 that species. This specimen does not appear to have come under the notice of Dr. 

 I'alconer. 



Species 3. — Plagiaulax F'alconeri, Oiocn. Plate IV, figs. IG and 16 a. 



This species is represented by the fore part of the right raandibidar ramus, with the 

 incisor and premolars, showing their outer surface ; followed by the impression of two 

 smaller molars, and part of the ascending ramus (PI. IV, fig. 16, nat. size, 16 a, magn. 

 3 diam.). The presented part of the jaw is rather less deep than in Plagiaulax Becklesii ; 

 the incisor is less broad in proportion to its length, especially at the base ; it is also more 

 convex on the outer side, and devoid of the longitudinal channel there (fig. 16 a, i) ; but 

 it is similar in length, position, curvature, and laniary character. The longitudinal 

 ridge or prominence [f, fig. 16 a) of the ranuis (answering to f in fig. 13 a) is here situated 

 half way between the alveolar outlets of the premolars and the lower border of the ramus ; 

 it is further from that border in PI. Becklesii (fig. 11, a, h), and is less definitely marked ; 

 the longitudinal channel below is less prolonged anteriorly. A single outlet of the dental 

 canal opens at a line dropped from the middle of the diastema between the incisor and 

 premolars. 



The first premolar [p 2, fig. 16 a) is larger than in PI. Becklesii ; its crown developes 

 the smooth protuberance above the fang, before flattening and expanding ; at two thirds 

 toward the apex it contracts thereto. The apex shows one short ridge dividing two 

 grooves ; it rises to the anterior angle of the crown of the succeeding premolar ; the form 

 of the crown is rhomboidal. The upper and posterior border is in contact with the 

 anterior border of the next tooth. The upper and anterior border slopes forward and 

 downward from the apex ; the two lower borders converge, as they descend, to the basal 

 protuberance. The height of the crown is one third more than its fore-and-aft breadth. 

 The small hind root is visible at its base. 



The second premolar {p 3) has a subquadrate crown ; but the outer enamelled surface 

 is rhomboidal ; the lower apex being formed by the basal protuberance. The upper and 



