64 ARCHAEOTHERIUM. 
disk of dentine, communicating by means of a narrow isthmus with a smaller 
disk, of the same form as the former, at the base of the anterior margin of the 
outer lobe. In the penultimate premolar the apex of the crown is worn off, leaving 
a subcircular dentinal surface continuous with a narrow tract, extending the length 
of the posterior margin. (IX. 3, 4.) 
The upper true molars of Archaeotheriwm, and the last premolar are inserted by 
three fangs; two external and nearly vertical, and a third internal, which is broad, 
and is apparently composed of two portions confluent. The penultimate premolar 
is implanted by two fangs, which are nearly vertical, and are placed one before the 
other. 
“Inferior Molars.—(VIII. 2; X. 2,3.) Of the lower molar teeth of Archaeotherium 
we have the true molars and the last premolar; but we have no opportunity of 
comparing them with figures of the corresponding teeth of Hntelodon. 
The crowns of all the true molars possess the same form, and differ only by 
successively decreasing from behind. They are oblong oval, and constricted at the 
middle, and are composed of two transverse pairs of conical lobes, with wrinkled 
sides. Posteriorly they are bounded by a conical tubercular heel, which relatively 
is not better developed in the last of the series than in those in advance; and 
anteriorly below the confluence of the lobes they are embraced by a thin basal 
cingulum. 
A remarkable peculiarity of a géneric character in these teeth is a transverse 
division of the apex of the antero-internal conical lobe, apparently as if this was 
composed of a confluent pair. 
The last permanent premolar is constructed upon the same plan as the penulti- 
mate premolar of the upper jaw. The crown is large, transversely compressed 
conoidal, and slightly curved backward, and is bounded anteriorly and posteriorly 
by a salient margin. At the base posteriorly a ridge exists with a festooned pro- 
longation on each side, and antero-internally a smaller and excavated talon exists 
with an outer simple and inner double festoon. 
The inferior true molars are inserted by two broad fangs placed one before the 
other, and consisting each of a connate pair; and the last premolar also has two 
fangs, but these are simple in their form. 
Temporary Dentition—(VIII.1,2; IX.1.) As in the Hog, the anterior two 
permanent true molars are fully protruded before the deciduous molars are shed, 
from which fact, together with the evident suilline character of Archaeotheriwm, it 
is reasonable to suppose the order in succession of the permanent to the caducous 
dentition is the same as in the former animal. 
The upper temporary true molar resembles the upper permanent true molars, 
but it is very oblique antero-internally, and all the lobes of the masticating surface 
except the two external are quite rudimentary. At the base of each outer lobe 
externally there exists a festooned ridge. 
The penultimate deciduous tooth has an antero-posteriorly elongated, trihedral 
crown; the posterior half of which is the broader, and is composed of a transverse 
row of three lobes, as in the true molar behind it, except that the internal one is 
