68 FOSSIL MAMMALIA OF THE 



anterior molar the foremost of the three cones or divisions of the crown is less than either 

 of the other two cones. The cingulum is more interrupted and more feebly developed 

 lluin in /J 4, or than along the outer side of the crown of m i (see fig. 18 b, ?« i); it 

 crosses obliquely the fore part of the front cone ; it also appears on part of the base of the 

 mid cone, and on the fore part of that of the hind cone, but feebly. The cones are low, 

 and worn ; the transverse breadth of these upper molars is greater than in their lower 

 liomotypes, yet the characteristic extension of the tooth in the antero-posterior direction 

 concurs, Avitli the trifid crown, in proclaiming the genus to which the present and pre- 

 ceding portions of upper jaw are referable. 



The tendency to turn, as it were, the outer side of the upper molars to the inner side 

 in the lower molars is exemplified in the partial development of the cingulum, as shown 

 in fig. 17a compared with its integrity in fig. 18 b. 



Confirmation of the ascription of fig. 17 to Triconodon ferox is afibrded by the sub- 

 jects of figures 1, 1a, b, c, PI. IV. Figure 1 gives the natural size of portions of an 

 upper maxillary of a right mandibular ramus (fig. 1 a, magn. 2 diam.), with the inner 

 surface exposed, and a siniilar anterior portion of the left mandibular ramus (fig. 1 c, 

 juagn. 2 diam.), with the outer side exposed, of the same skull. 



A portion of the bony palate projecting from the matrix is crushed down below its 

 level, so as to obscure the inner smface of some of the teeth. The crown of the molar 

 (fig. 1 A, magn. 4 times) shows the thickness of the cingulum traversing the outer side 

 of its base, characteristic of the upper molars of Triconodon. A more interrupted 

 growth of 'cingulum' on the inner side increases the transverse basal breadth. The 

 inferior height of the anterior cone indicates this to be the first molar {m i). Of the pre- 

 molars two are preserved, showing a principal cone, a hind smaller one, and the additional 

 basal cusp due to the further extension backwards of the cingulum, as inj^j 4, fig. 17, 

 PI. III. 



The portion of right mandibular ramus, in contact with its maxilla (PI. IV, fig. 1 b), 

 is mainly instructive in showing a second incisor [i 2) in place ; it is the tooth in advance 

 of that shown in fig. 7, PI. Ill ; it is smaller in size but similar in shape to the third 

 incisor {i 3). 



The canine (c-) has the usual laniary shape, slightly recurved ; the apex is wanting, it 

 appears to be worn down ; there is a longitudinal basal indent at the inner side of the 

 crown here exposed. The first premolar and its socket are crushed out of view ; the 

 crown of the second premolar {p 2) is in place, showing the chief cone with a short sub- 

 vertical fore margin, a long sloping hind margin, provided with a basal cusp, which 

 extends the cingulum. The latter feature is more strongly marked along the inner side 

 of the base of the third premolar {p 3) ; its fore end, as it circumscribes that part of the 

 base of the main cone, simulates a small basal talon ; the hind end similarly projects 

 beyond the true basal cusp or talon at that part of the main cone. The two-cham- 



