98 MACHAIRODUS. 
the first premolar, presents the commencement of a ridge, which no doubt passed 
to an alary process of the symphysis, such as exists in Machairodus neogaus 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—(P1. 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 first 
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 genus, 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 Muchairodus. 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 surface 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 Machairodus neogaus, 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 cusp, 
