PURBECK FORMATIONS. 59 



to the original description that at the posterior margin of the posterior cone a rudimental 

 talon is feebly marked off by a short vertical indent from the rest of the outer surface of 

 that cone. 



The first of these teeth (fig. 7 a, m i) is very little less than the others ; the fore ridge 

 of the base of the coronoid (c) screens part of the last cone of the third molar {m 3 ) from 

 view. 



The last premolar [p 4) seems to have slipped some way from its socket, exposing its 

 two roots, and bringing the base of its crown on a level with the apices of the cones of 

 the succeeding molars. The crown of jo 4 has a principal subcompressed cone, with a 

 small and low anterior basal cusp, and a larger and higher posterior one. The two divisions 

 of the socket of the premolar in advance {p 3) indicate a tooth of rather inferior size. The 

 next premolar (^ 2) is much less, but of like character; the main cone, however, is much 

 reduced in proportion to the basal cusps. The indications of teeth anterior to jo 2 are 

 obscure; they show, however, the socket of a minute two-rooted anterior premolar {p \), 

 the apex of an emerging crown of a canine (c), and one, or perhaps two, of the sockets of 

 the small incisors. 



An outlet of the dental canal opens beneath the socket of jo 1, midway between the 

 upper and lower borders of that part of the jaw. 



The symphysis rises rather abruptly from the lower border, sloping at an open angle 

 therewith, more resembling that part in Sarcophilus than in Thylacinus, where it tapers 

 forward more gradually. 



The lower border of the ramus is nearly straight, very feebly wavy, from the convexity 

 below the molars, which is repeated rather less feebly below the crotaphyte depression : it 

 is obtuse, rounded, losing thickness as it recedes to beneath the rising branch. The 

 crotaphyte depression is there bounded by a low ridge («'), extending backward to the 

 outer and under side of the condyle [h), as in Thylacinus, only more depressed, so as to 

 cause the slight convexity of that part of the lower contour of the jaw. In advance of the 

 crotaphyte depression a more shallow longitudinal one extends some way forward, just 

 above the rounded lower border of the ramus. 



The condyle {b) is large, convex both transversely and vertically, most extended in the 

 latter direction ; it projects from a level a little below the outlets of the alveoli. The 

 notch between it and the coronoid process gives the condyle a subpedunculate character 

 (this is better marked in the larger species of Triconodon). So much of the coronoid 

 process as remains does not extend back so far as the hind part of the condyle, but the 

 process might have done so when the apex was entire. 



From the relation of the last molar [m 3) to the fore margin of the coronoid, and the 

 degree of protrusion of the crown of the canine, this specimen may be concluded to 

 have come from an individual not quite fully grown. 



I 



am led to the same inference by the appearance of the less complete specimen 



