64 ARCHAEOTHERIUM. 



disk of dentine, communicating by means of a narroAV 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 oif, 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 Archaeotheriwin, 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 jDenultimate 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 ArcJiaeofherimn 

 we have the true molars and the last premolar; but we have no opportunity of 

 comparing them with figures of the corresponding teeth of Entelodon. 



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 generic 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 fongs 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 Archaeotlierium, 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 



