Temnocy&a and Hypotemnodon. — Eyerman. 285 
ter in the type of Temnocyom is at the anterior and the cone 
rising from this portion of the crown, in the new genus, the 
greatest diameter is at the centre with the cone rising 
therefrom. 
In //. coryphceus the transverse diameter of iiiJ is less than 
in the type of Temnocyon ; the denterocone, which is of equal 
development in both, is in the former species separated from 
the protocone lrv an elongated neck, which dilf'ers very much 
from the robust development at this point in the latter species ; 
the protocone has rather a more cylindrical shape, inclined 
backward, than (as in T. altigenis) an erect pyramidal one. 
Above the anterior portion of this tooth in Hypotemnodon the 
malar bone projects over the maxilla, but in Temnocyon above 
the middle of ™. l. 
In ELi the external edge inclines backward and outward to 
a greater extent than in the t} r pe of Temnocyon and in this 
species the para- and metaeones are crossed by a ridge which 
gives the two cones a laterally compressed appearance: this 
is absent in Hypotemnodon ; nor is the groove between the 
two cones so well defined; the protocone is more flattened and 
is nearer the middle of the internal edge and the internal cin- 
gulum is less well defined than in the type species; imj is so 
badly worn as not to admit of comparison; the transverse di- 
ameter is 12 mm. in T. altigenis and 8 mm. in //. coryphaeus, 
while the antero-posterior is 7 mm. in the former and 4 mm. in 
the latter. 
p. 3 and i and succeeding molars of Hypotemnodon and p. 2-3-4 
and m. 1 and 2 of T . altigenis only are available for comparison. 
In the several species of Temnocyon the width of the lower 
jaw decreases in proportion to the decrease in length, but in 
Hypotemnodon the decrease is less and not in proportion to 
the length. P71 is slightly larger than in Hypotemnodon and 
is of simple structure. In the latter genus a small metaconid 
is developed and there is an incipient cusp at the anterior ex- 
tremity, as well as a posterior marginal lobe. The tooth ex- 
hibits a good type of the cutting structure. i\ i is nearly 
identical in both species, with the following exceptions: the 
tooth is more compressed and exhibits a more marked cutting- 
structure than in Temnocyon and the talon is more elongate 
and the metaconid less strongly developed: the greatesl 
