204 Mr. Owen on the Fossil Remains of a Mammal 



The molars are seven in number on each side, and resemble more nearly those 

 of the Chferopotamus than the molars of any other known genus of existing or ex- 

 tinct Mammalia. They consist of four spurious molars (prcmolares) and three 

 true molars (^molares), PI. XXI, 



The first and second spurious molars, counting from before backwards, have 

 simple subcompressed crowns, surmounted by a single median conical cusp with 

 a small anterior and posterior tubercle at the outer side, and a ridge along the 

 inner side of its base : they are separated from each other by an interspace nearly 

 equal to the antero-posterior diameter of the first molar, which measures two lines 

 and a half. The second and the remaining molars are in close juxtaposition. The 

 third and fourth false molars present a sudden increase of size and of complexity 

 of the grinding surface, with a corresponding change of form. The plane or trans- 

 verse section of the crown is subtriangular with the base outwards and nearly 

 straight, the apex inwards and a little forwards, rounded off, to which the anterior 

 and posterior sides converge in curved lines ; the grinding surface supports three 

 principal tubercles or cusps, two on the outer and one on the inner side : there are 

 two smaller elevations, with a depression on the summit of each, situated in the 

 middle of the crown, and the whole is surrounded with a ridge, which is developed 

 into a small cusp at the anterior and external angle of the tooth. These teeth 

 form the principal difference between the dentition of the present genus and that 

 of the Chreropotamus , in which the corresponding false molars are relatively smaller 

 and of a simpler construction, having only a single external pyramidal cusp, with 

 an internal transverse ridge or talon at its base. The true molars, three in num- 

 ber on each side, closely correspond in structure with those of the Chceropotamus. 

 They present four principal conical tubercles, situated at near the four angles of 

 the quadrilateral grinding surface. Each transverse pair of tubercles is connected 

 at the anterior part of their base by a ridge, which is raised midway into a smaller 

 conical tubercle with an excavated apex. The crown of the tooth is surrounded 

 by a well-marked ridge, which is developed, as in the third and fourth false molars, 

 into a sharp-pointed cusp at the anterior and external angle of the tooth. The 

 hindmost molar is more contracted posteriorly, and its quadrilateral figure less 

 regular than the two preceding molars. 



The sockets of the canines or tusks indicate that these teeth were relatively as 

 large as in the Peccari ; and that they were directed downwards as in that species, 

 and as most probably also in the ChcBropotamus. The temporal muscles were as 

 well-developed as in the Peccari, the depressed surface for their attachment ex- 

 tending on each side of the cranium as far as the sagittal suture. 



The frontal bones are divided by a continuation of the sagittal suture. The na- 



