PETERSON : A REVISION OF THE ENTELODONTID 85 
of the tooth at its postero-internal portion. ‘The two small cusps are nearly on a 
direct transverse line and immediately external to the tetartocone. Anteriorly and 
posteriorly there are very heavy cingula ; externally and internally the cingulum is 
only moderately developed. The deciduous P* was found quite close 
to its position and there is comparatively little, or no doubt, that this 
tooth belongs with this specimen. The tooth is molariform, as in the 
Oligocene genus (87, p. 287). It is strikingly similar to M2 of the 
permanent series, but has the antero-external portion of the cingulum 
developed into a more decided cusp.” Anteriorly there are three 
cusps on the crown: one internal, one external, and one directly an- 
terior. The two former are of equal size, while the latter is quite 
small and occupies the anterior exit of the longitudinal valley. Pos- 
teriorly there are two subequal cusps which are separated from the 
Fia. 32. Sup- 
anterior cusps by a deep cross-valley. The tooth is nearly surrounded 
. posed Deciduous 
by a cingulum. Upper First Pre- 
The chief feature of the maxillary bone is. its comparatively molar. Nat.size. 
(Carn. Mus. Cat. 
. i ¥ Vert. Foss., No. 
gether in the alveolar border than is the case in the adult; the preor- 9197.) 
short antero-posterior diameter. The premolar series is set closer to- 
bital foramen, however, seems to occupy the same relative position as 
in the latter. he palatine plate is quite thick, but its transverse diameter is small. 
The milk dentition of the lower jaw is represented only by the last molar (No. 
2137A, Carn. Mus. Cat. Vert. Foss.). ‘he crown of this tooth is composed as. usual 
of three transverse pairs of cusps and a small talon developed by the cingulum on 
the posterior face. The tooth is very long and narrow with broad transverse valleys 
separating each pair of tubercles, while the longitudinal valley is much less distinct. 
The crown is supported by two strong fangs which are bifurcated near their lower 
extremities. The posterior portion of a lower jaw (No. 2137A,’ Carn. Mus. Cat. 
Vert. Foss.) was found near the tooth described above and undoubtedly belongs to 
it. In this mandibular fragment the posterior alveolus for dPy is still preserved, 
and into this the tooth referred to fits quite perfectly and is regarded by the writer 
as belonging to the same individual (see Pl. LIX, fig. 3). When the jaw is exca- 
vated from the inner side back of the last milk-molar there is seen the complete 
crown of M;, and only the anterior portion of My. The crown of My is directed 
upward in the usual way, while that of My is directly inward, and would have to 
rotate outward and upward in order to erupt through the alveolar border in the 
usual manner. As is seen from the illustration (PI. LIX, fig. 3) the two anterior 
33 Professor Scott evidently mistook the anterior part of the tooth he described for the posterior portion (J. ¢., p. 276) 
