98 MACIIAIRODUS. 



the first premolar, presents the commencenient of a ridge, wliicli no doubt passed 

 to an alary process of the symphysis, such as exists in Ifachairodus neogaiis and 

 other species. 



Nine lines of the hiatus in advance of the molars exists in the specimen, without 

 any disposition anteriorly to expand for the accommodation of the canine alveolus. 

 Its margin is acute, and, viewed from the broken part, appears a little everted. 

 Below it externally the surface slopes in a slightly convex manner outwardly to 

 the base of the bone, and it presents two small mental foramina. 



Dentition. — (PI. XVIII. 1, 3, 4, 5.) The upper jaw in the specimen contains the 

 incisive alveoli filled with matrix, portions of the canines, the alveolus for the fii'st 

 molar, and all the other molars except the posterior two of the left side. The 

 lower jaw contains only the molars. 



Characteristic of Machairodus, the superior incisive alveoli indicate the possession 

 of larger incisors than exist in Felis. Laterally they border so closely on the 

 canine alveolus that a smaller hiatus is left than in other species of the gentis, and 

 they increase in size from the first to the last. 



The upper canine (1) is laterally compressed, and is relatively much less broad 

 than in Machairodus neogaus, and was about half as long and broad as that of 

 Machairodus cultridens. In the fragment, preserved in the specimen, the posterior 

 sub-trenchant edge, about ten lines below the enamel border of the crown, com- 

 mences to be crenulate, as in other species of Machairodus. Antero-internally there 

 exist the remaining three lines of a ridge, which commences near the enamel 

 border and proceeds downward and forward, and at its lower third is also crenu- 

 lated. In section the upper canine is elliptical, and is acute posteriorly, and at the 

 enamel border of its crown measures seven lines and a half in breadth, and about 

 four lines and a half transversely. 



The first superior molar, as indicated by the remaining alveolus, had a simple 

 mammilloid crown, as in Felis. The alveolus is subrotund, about one and a half 

 lines in diameter, and borders closely upon that for the canine. 



Posterior to the first molar, a relatively very large hiatus exists compared with 

 that of Felis and other species of Machairodus, being four lines in length, or equal 

 to the whole interval between the canine and second molar of Machairodus neogaus. 



The crown of the last mentioned tooth (3), compared with that of the Panther, 

 is shorter relatively to its breadth, and in comparison of size with that of the 

 carnassial tooth is relatively very much smaller than in any species of Felis. Its 

 outer sui'face has the same inclination and prominent base as in the latter, but is 

 less convex. It is composed of a median compressed mammillary cusp, with a 

 trenchant margin, a small anterior lobe, as in Macliairodus iieogaus, and a posterior, 

 simple, compressed mammillary lobe with a trenchant border, relatively equal to 

 the corresponding pair in the latter species and in Felis. 



The crown of the upper carnassial tooth (1) has about the same relative size as 

 in the latter genus, and also the same degree of inclination of its outer surface, 

 but it does not possess the lenticular fossa at the conjunction of the median cusp 

 with the posterior lobe. The anterior lobe descends much lower than in Felis, so 

 as to shorten very considerably the corresponding margin of the median cusjj. 



