A NEW FOSSIL PACHYDERM. 



259 



vex than the internal, and marked near the base of the enamelled 

 portion with an acute, elevated line, which runs obliquely to the 

 anterior edge, where it is met by a similar less elevated line belong- 

 ing to the internal face (fig. 10) ; this latter line is acutely angu- 

 lated at the base, and joins another elevated line which arises near 

 the angle in the line defining the enamelled surface, and continues 

 parallel to the anterior margin about half-way to the extremity, 

 where it gradually vanishes. The anterior margin is worn into a 

 very narrow surface, extending from a to the extremity, b (fig. 9). 

 The inserted portion of the tooth is slightly sinuous on the anterior 

 margin, and is marked with two very feeble grooves on the external 

 surface ; the space between these grooves is rather more convex 

 than the adjoining parts. At c (fig. 9), the fang is slightly con- 

 tracted. 



The only teeth I have seen figured, which can be compared 

 with the present specimen, are the canines of the genus Machai- 

 rodus, which are, however, distinguished by the curiously serrate 

 edges, and the absence of the oblique basal lines so characteristic 

 of Platygonus. 



The superior premolars are shown in figs. 12 and 13 (p. 3, p. 4). 

 That p. 4 (fig. 13) must be considered a premolar is evident from 

 an inspection of fig. 2, in which are seen three premolars in place, 

 while the socket of the fourth is quite distinct. In my notice of 

 this genus in Silliman^s Journal (loc. cit. p. 103), it is stated that 

 there are but three premolars ; I had not then cleaned away the 

 cement in which the socket (p. 4, fig. 2) was concealed ; I also 

 considered m. 1 (fig. 13) as the penultimate molar, but on compar- 

 ing it with the tooth anterior to fig. 13', it shows minute differences, 

 which will be detailed below. 



The first premolar, right side, p. 1 (fig. 12), is triangular, with 



