32 PROCEEDINGS OF THE GEOLOGICAL Society. [June 16, 
molar being closely approximated, in conformity with the contracted 
breadth of that part of the crown. 
The enamel which invests the crown is almost a millimeter in thick- 
ness: the fine striz indicative of its successive formation are obvious ; 
but otherwise its surface is smooth and polished. The cement cover- 
ing the fangs is thinner ; the coronal cement does not fill up any of 
the cavities of the crown. The molar teeth in relation to each other 
hold the same slightly oblique position and zigzag outer contour as 
in Paleotherium ; the anterior and external angle of the hinder 
molar projecting outwards beyond the crown of the next molar in ad- 
vance, and so with the rest. The six grinders progressively increase 
in antero-posterior extent as they recede in position, from P 2 to 
M 3. 
The chief distinctive character of the true molars, as compared 
with those of the genus Paleotherium, is the detachment of the inner 
portion of the antero-internal oblique ridge (‘ colline transversale an- 
térieure,’ Cuv.) as a distinct lobe or tubercle p, and its superior thick- 
ness to the other part of the ridge z. It is not so thick and round 
as the homologous lobe in the Anoplotherium (fig. 5, p), and it forms 
an oval instead of a rounded dis¢ of dentine when moderately worn, 
as in m 2, fig. 2; but it then gives the crown of the tooth a character 
which brings it very close to that in the Anoplotherium: for which 
indeed it might, if insulated, be mistaken, according to the differen- 
tial character laid down by Cuvier*. The entire molar series in the 
upper jaw resembles that of the dnoplotherium in the progressive in- 
crease of the size of the crown from the foremost to the hindmost tooth: 
the molars are more equal in Paleotherium. 'The premolars differ 
in their smaller number from both Paleotherium and Anoplotherium ; 
but those answering to p 2 and p 3 (Odontography, pl. 135. fig. 2) 
resemble in their smaller size and comparatively simple structure the 
corresponding teeth of the dnoplotherium more than they do those of 
the Paleotherium. . 
The true molars not only differ from those of the Anoplotherium 
(Pl. III. fig. 5) m the comparatively smaller size and more compressed 
form of the conical tubercle p, but in the more open angles of the 
outer lobes 0, o', and im the less curved form of the ridge 7, which is 
separated from the posterior outer crescent by the deep fissure (a). 
In these latter differences the Paloplotherium resembles the Paleo- 
therium, to which genus it approximates in the development of the 
canine teeth, and their separation, in the upper jaw, by a diastema 
from the premolars. But in the characters above specified, by which 
the Paloplothere differs from the Palzeothere, it approaches the Ano- 
plothere ; it differs, however, from both genera in the absence of the 
first premolar (P 1): of which not a rudiment or trace is present, 
although the last molar has not come into use. 
One may associate with the absence of this premolar the relatively 
longer interspace which divides the first of these teeth (P 2) from 
the canine in the upper jaw of Paloplotherium: im the specimen 
under description this space measures 9 lines (2 centimeters), which 
¥ ‘Tom. cit. p. 21. 
