P. BECKLESII AND P. MINOR. 417 



on the matrix of the slab which contains the hind fragment, 

 so that it has been easy, by combining the figures, to pro- 

 duce a restored outline of the general contour, which is shown 

 by the aid of dotted lines, in both figures, magnified twice 

 the linear dimensions. 1 The most striking characters are : 

 1st, the shortness of the jaw from the posterior edge of the 

 ascending ramus to the border of the alveolar sheath of the 

 incisor (a) ; 2nd, the great vertical height of the horizontal 

 ramus in relation to the last dimensions ; 3rd, the depressed 

 position of the condyle (d), and its great horizontal projec- 

 tion behind the coronoid process. The lower body deviates 

 little from the horizontal for about four-fifths of its length, 

 being but slightly convex. The upper margin slopes a little 

 downwards from behind the premolars on to the incisive 

 alveolus, so that if the two margins were produced they 

 would meet at an acute angle. The diasteme is very short. 

 The incisor (a) is comparatively large and directed suddenly 

 upwards, the point being elevated above the level of the pre- 

 molars, with a short bluff sheath-border. The base of the 

 incisor is impressed with a shallow longitudinal fossa, and 

 the upper edge is bevelled. The point shows no mark of 

 abrasion. The mentary foramen is small, indistinct, and 

 situated mesially in a line nearly with the middle of the 

 diasteme. The alveolar border rises in large serrate pro- 

 cesses between the fangs. The dark-shaded depression (fig. 

 4, i) behind the vertical fracture (at b) upon the matrix 

 marks the position of the pointed gibbosity on the inner side 

 of the alveolus of the last true molar. It is considerably 

 below the line of implantation of the premolars, indicating 

 that the true molars were placed correspondingly low, as is 

 seen in the jaw of the other species. The longitudinal me- 

 dial shade shows a deeply impressed broad channel upon the 

 outer surface of the ramus, which is most pronounced, under 

 and behind the last premolar. The amount of this depres- 

 sion is well exhibited by the vertical sections (PI. XXXIII. 

 figs. 2 and 3, / and g), where (*) represents the inner surface, 

 and (y) the outer. It is seen that the inner surface is slightly 

 concave in the vertical direction, between the upper and 

 lower margins ; and that the general convexity of the outer 

 surface is interrupted by a wide and deep fossa, causing a 

 mesial constriction (y). Although there is as yet no direct 

 evidence to the point available, in conseq^^ence of the outer 

 surface of the posterior portion being adherent to the matrix, 

 still it would appear that this channel runs back towards the 



1 See also fig. 1 of PI. xxxiv., illus- I younger individual magnified four times, 

 trating a perfect right ramus of a | 

 VOL. II. E E 



