Cope.] ‘ 494 [Sept. 17, 
The dimensions of the superior molars increase to the penultimate, 
while the external and posterior sides of the last molar are contracted, re- 
ducing its size. The external faces of the external Vs of the true molars 
are considerably impressed ; those of the premolars are nearly flat. 
The second premolar is two-rooted, and has a compressed crown, with- 
out either heel or cingulum, except a thickening of the posterior base. 
The base of the crown is triangular. The external plate of the third pre- 
molar is simple, and is connected with the internal cusp by a cingulum 
on the posterior base of the crown. The crown is transverse, and the 
inner tubercle rather small. The fourth premolar is much larger than the 
third. Its external plate is divided into two apices, which are not im- 
pressed. Their external faces are separated by a faint ridge, and are 
divided medially by a faint ridge. The anterior external angle is rather 
prominent. The anterior and a posterior cingulum extend to and round 
the inner base of the interior tubercle. Within the anterior external apex, 
is a well developed intermediate crest parallel to it; and there is a corres- 
ponding crest within the posterior external apex. This one turns inwards 
at its posterior extremity, which is on the posterior cingulum. 
The anterior angle or horn of each external crescent of the true molars is. 
very prominent. They are sections of short vertical ridges, which unite 
near the base of the crown, giving abruptness to the impression of the ex- 
ternal surface of the anterior lobe. The middle of each face has a faint 
median ridge. The two molars have an anterior basal cingulum, but no 
posterior or internal, excepting a trace between the bases of the internal 
lobes. The anterior intermediate crescent is quite parallel with the ex- 
ternal ; the anterior internal tubercle has a slightly V-shaped section. The 
posterior inner tubercle is quite confluent with an oblique intermediate 
crest, as in UW. chamense. In the last true molar, as there is only one in- 
ternal tubercle, this crest is short, terminating at the posterior border. 
The last true molar is like the last premolar, except in its two impressed 
external crescents. 
A fragment of the right branch of the lower jaw supports two molars, 
and the alveoli of two others, all of which have two roots. These teeth 
are the four premolars, although the last one has the form of the first true 
molar. Should my surmise be correct, then the third premolar has nearly 
the same form and structure as the fourth. The anterior horn of its ante- 
rior V is not produced quite so far inwards as in the fourth tooth. At the 
point of junction of the adjacent horns of the Vs there is a slight antero- 
posterior extension, forming a median buttress of the inner side of the 
crown as in Anchitherium. The posterior horn of the posterior V is also 
incurved, as in that genus. The angles of the Vs of the inferior molars 
are rounded. 
The surfaces of the enamel of the teeth of both jaws is smooth. 
Measurements. M. 
Length of superior molars, less P-m. I .........-20-.005 046 
«« of true molar series....... sashes execs samen 028 
“of base of P-m, II..... Pe er et eer sed aaiied 005 
