82 MEMOIRS OF THE CARNEGIE MUSEUM 
The inferior premolars of ntelodon are relatively large, more regular in size, 
and Ps and P; are entirely surrounded by cingula; while in Dinohyus the premolar 
teeth as a whole are smaller, P; being conspicuously the larger of the series and Ps 
and P; have the cingula less strongly developed. 
The molar series in Dinohyus is very crowded and occupies less than one half 
of the antero-posterior diameter of the alveolar border. As in other allied genera, 
the molars are of relatively small size in comparison with the jaw and they increase 
Fic. 31. Crown View of Inferior Dentition, Left Side. Type specimen of Dinohyus hollandi Peterson. 3 nat. size. 
(Carn. Mus. Cat. Vert. Foss., No. 1594.) 
in size posteriorly. M, is considerably worn in the type, so that the quadrituber- 
cular pattern is converted into two heavy transverse tracts having irregular outlines 
and with only a remnant of the cross-valley on the inner half of the tooth. On the 
antero-internal angle the cingulum is developed into a small basal tubercle. Oppo- 
site the cross-valley there are short and smoothly rounded cingula externally and 
internally. On the postero-external angle is a cingulum, which is continuous with 
a similar short cingulum on My. ‘The posterior face of the tooth is closely crowded 
against the anterior face of Mz. ; 
In the type the quadritubercular pattern of Mg is plainer than is the case in 
the tooth just described, but trituration has already caused the appearance of the 
solid cross-crests; the anterior being slightly more elevated than the posterior. An- 
teriorly there is a deep, narrow fissure, which is caused by projecting horns from the 
proto- and metaconids. On the external face the cingulum extends from the 
postero-external base of the protoconid and continues around the hypoconid, termi- 
nating in the posterior basal heel:* ‘There is no cingulum on the external face of 
the protoconid, nor on the internal face of the inferior molars. 
The proto- and metaconids of M, are very little worn, so that the separation is 
still present, but it is reduced to a very narrow and shallow fissure on account of the 
82In my preliminary notes on (Dinochwrus) Dinohyus hollandi, Science, Vol. XXII, p. 212, 1905, 1 made the state- 
ment that ‘‘ There is no cingulum on the inferior molars,”’ which is incorrect. 
