176 
PHENACODUS. 
Measurements of superior molars. 
Length of the last five molars. 
Length of the penultimate premolar. 
Width of the same..... 
Height of the same.. . . 
Length of the last premolar. 
Width of the same.. . 
Length ot' th’e first true molar.... 
W^idth of the same... 
Height of the same. . . . 
Length of the last true molar. 
Width of the same. 
Height of the same. . . . 
M. 
0. 064 
0. 012 
0. 010 
0. 008 
0. 013 
0. 013 
0. 011 
0. 016 
0. 007 
0. 015 
0. 015 
0. 006 
The posterior inferior molar of the same side is wide in front, and reg¬ 
ularly oval in posterior outline, and has two equal anterior and three une¬ 
qual posterior tubercles. One of the posteriors is situated near the middle 
of the outer side, and is separated from the adjacent anterior by a deep 
groove. The corresponding inner tubercle is more posterior; anterior 
tubercles low, trihedral, and connected by a shelf-like cingulum across the 
front of the tooth; rudimental cingula on outer side of crown. The penulti¬ 
mate molar has three ’tubercles on the posterior border; and a deep fissure, 
corresponding to that of the last molar, separates one of them from the 
anterior tubercle. In all of the true molars, the posterior outer tubercle is 
connected with the anterior inner by a low oblique ridge, which forms the 
external border of a shallow basin-like concavity of the crown. The ante¬ 
rior inner tubercle is stouter than the anterior outer, especially in the first 
and second true molars; in the latter, it has a posterior enlargement, which 
is, in the former, separated from the anterior part by a fissure-like groove. 
The last premolar is longitudinally oval at the base, the anterior extremity 
the narrower. The crown supports two median tubercles, the outer the 
more elevated and anterior. There is an angular basal tuberosity in front, 
and a posterior heel-like portion. The external angle of this part is broken 
away, but it probably supj^orted a tubercle, as an oblique ridge extends 
from its position inward and forward. No internal posterior tubercle. 
The portion of the mandibular ramus preserved presents nothing 
remarkable. It is stout and convex on the external face. The coronoid 
process rises rather abruptly a, short distance l)eliind tlie last molar, and the 
