248 MEMOIRS OF THE CARNEGIE MUSEUM. 
recent horse, the roots are less curved, and the crowns generally have received 
little wear, except in the case of old individuals in which the median pair, and 
sometimes the second pair, have received wear at the points of the crowns, which 
may indicate that there were upper incisors. The incisor series has a procumbent 
position not unlike that in the recent horse, though the transverse diameter of 
the symphysis is considerably less than in Equus. There is no canine in Moropus, 
nor in Nestoritherium, so far as known; but in Macrotherium and in Circotherium 
there is a well-developed canine, in the former genus located close to the incisor series, 
in the latter genus rising prominently at the posterior edge of the edentulous incisive 
alveolar border and separated from the premolars by a moderately long diastema. 
In Moropus there is a long diastema back of the incisors, which is succeeded by 
a series of well-developed cheek-teeth corresponding to the large upper teeth. 
The lower cheek-teeth are on the whole more nearly like those in Titanotherium than 
are the upper. P,is absent. P:is quite simple and much reduced, while P; has the 
typical molariform pattern observed in P, of Titanotherium. In the lower jaws which 
belong with the cranium associated with No. 1604 the dentition is very much worn, 
especially the premolars, so that the detailed structure of the crowns is less distinct, 
but other specimens are more perfect in this respect. P, is much increased in the 
antero-posterior direction and has the complete W-shaped character of the crown, 
the postero-internal angle being especially well developed. Externally the cingulum 
is well developed, while internally the tooth is nearly smooth; this is also true of P3. 
M, of specimen No. 1604 is very much worn; its antero-posterior diameter is 
considerably greater than that on P,; the crowns of the two teeth are otherwise 
quite similar, except that on M, the hypoconid is more developed; while the cingu- 
lum is less prominent. M, is longer, but is otherwise of the same general pattern 
as the tooth preceding it; the cingulum, however, is more prominently developed 
on the external and posterior faces of this tooth. M3; lacks the third lobe which 
is of the usual pattern seen in the European and Asiatic species of this family. 
Externally and posteriorly the cingulum is well-developed, while internally the 
tooth is more or less smooth. 
MEASUREMENTS OF Moropus elatus (Car. Mus. Cat. Vert. Foss. No. 1604). 
Mm 
Length) of premolar-molarisenleser ae eee aac eee Ore cee emcer 202 
Antero=posterion diameter on crowmlolliae eens eerie 9 
iransverse diameter olcrowDi Ole meee rreieeieee ice cee eerie 11 
Transverse (greatest) diameter of crown of Ip...............-e eee eee eeee 12 
Transverse (greatest) diameter of crown of I3.................--.--+--ee- 9 
Antero-posterior diameterolRerc mene oe eae oe ee ere eer eras 19 
