1857.] FALCONER PLAGIAULAX. 267 



attained the magnitude of a separate tubercle. The two inner points 

 form obtusely conical tubercles, which are in greater relief, and less 

 affected by wear ; so that the worn disc of the outer row shows like 

 a step at their base. Of these tubercles the anterior bears an acces- 

 sory lobe which is continued across in a front talon, giving a bilobed 

 character to the point, which is but slightly abraded at the apex ; 

 while the posterior point shows a well-marked depressed disc, which 

 is continued some way down upon the inner side of the enamel, as if 

 caused by the grinding play of an overlapping cusp of an upper tooth 

 in use against it. The longitudinal furrow between the two rows is 

 distinctly visible. There is a well-defined basal cingulum to the last 

 molar in this species. The inside elevation of the last true molar 

 agrees very closely with a corresponding view of the larger tooth of 

 Microlestes antiquus, as represented in one of the drawings belonging 

 to Sir Charles Lyell (fig. 17, c). The second and last true molar 

 presents a nearly square crown with rounded angles. It is fully equal 

 in size to the penultimate, if not a little larger. The crown bears two 

 marginal edges, as in the other species, with a well-marked depression 

 between them. The inner* edge is broken off and seen imbedded in 

 the matrix of the opposite slab. The outer edge is entire, but ground 

 down by wear, so that it shows a marginal band with no remains of 

 crenation. The detrition of the crown, as a whole, bears some resem- 

 blance to that seen upon the last molar of an aged Bear ; the com- 

 parison, be it understood, not being intended to imply the slightest 

 idea of affinity. The angle formed by the anticlinal planes of the 

 crowns of the true molars and premolars is more acute in the jaw 

 of Plag. Becklesii than in that of Flag, minor. 



Character of the Lower Jaws. — Although the teeth are seen in 

 greater perfection in the latter species, the other characters of the 

 jaw are best shown by the specimen of Play. Becklesii, figs. 1 & 4, 

 a, b, & c, d. The jaw, right ramus, is broken vertically through 

 one of the sockets of the first true molar ; the anterior fragment 

 {a, b) presents the outer surface of all in front, from the last pre- 

 molar, while the posterior fragment (c, d) exhibits the inner sur- 

 face of all behind, on to the condyle. A very distinct impres- 

 sion of the premolars attached to the anterior piece, is left on the 

 matrix of the slab which contains the hind fragment, so that it has 

 been easy, by combining the figures, to produce a restored outline 

 of the general contour, which is shown by the aid of dotted lines, 

 in both figures, magnified twice the linear dimensions *. The most 

 striking characters are : 1st, the shortness of the jaw from the pos- 

 terior 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 de- 

 pressed position of the condyle (c?), and its great horizontal pro- 

 jection behind the coronoid process. The lower border of the body 

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



* See also fig. 14, p. 280, illustrating a perfect right ramus of a younger indi- 

 vidual magnified four times. 



