74 TITANOTIIERIUM. 



AXTEEO-POSTERIOK. TKANSTEKSE. 



Inches. Lines. Inches. Lines. 



Last true molar 4 2 1 11 



Second true molar ........2 9 1 9 



First true molar ........ 17 



The isolated crown above mentioned of an inferior left premolar (PI. XVI. Figs. 

 8-10), probably the second, measures only sixteen lines antero-posteriorly, and 

 almost an inch transversely, indicating a rapid reduction in size of the teeth from 

 behind forward; nevertheless, this is gradual, for the fangs of the last premolar, 

 still retained in the portion of lower jaw, on a line with the connection to their 

 crown, measure twenty-one lines antero-posteriorly. The inner side (Fig. 10) of 

 the specimen of the premolar is a smooth vertical plane; and externally (Fig. 9) 

 the basal ridge is deep, but thin, and rises to the most pi'ominent part of the lobes, 

 as upon the true molars. The masticating surftxce (Fig. 8) presents a broad tract 

 of dentine bordered by enamel, bilobed externally, and straight internally. 



The crown of the inferior canine (PI. XVI., Figs. 11, 12) is curved conical in 

 form, and, in section at its base, is \ery nearly circular. Internally, its base is 

 embraced by a thick, deep cingulum, with a prominent margin, which exhibits also 

 a tendency to pass around the outer side of the tooth. The outer (Fig. 11) and 

 inner (Fig. 12) sides of the tooth are defined by a saliance of the surface, and the 

 former is uniformly convex and smooth, the latter angularly convex, less broad, 

 and less smooth. The enamel is worn off from the point of the tooth, and also 

 below this antero-externally over an oval space almost half an inch in length, indi- 

 cating that the inferior canine, as in the undoubted Palaeotherium,^ occupies a 

 position, when the mouth is closed, posterior to the superior canine. 



Measurements of the crown of the inferior canine are as follows : — 



Inches. Lines. 

 Circumference at base .......... 3 



Length of external convex surface ........ 1 7 



Height from the base internally . . . . . . . . 1 2 



Of the two fragments of upper molars above mentioned, one is the internal half 

 of the crown of a premolar (PI. XVII., Figs. 5, G), probably the second; the other 

 is an internal portion of a true molar (PI. XVI., Figs. 6, 7). 



The former specimen measures one inch five lines antei'o-posteriorly, and its 

 masticating surface (PI. XVII., Fig. 5), which is very much worn down, presents 

 a form intermediate to that in the corresponding tooth of PalaeotJierum magnum, 

 and AceratJierium incisicum. Internally (Fig. G), the crown is transversely convex, 

 and is very sloping inwardly from the fiings, so that the tooth has projected very 

 considerably internal to the alveolar margin of the palate. This side of the tooth 

 is formed by a thick and deep cingulum, which envelops the bases of the inner 

 lobes, and exhibits an obtusely rounded margin, thickest anteriorly. 



The inner lobes, of which the anterior is very much larger than the posterior, 

 are confluent, and, in the specimen, are nearly worn to their base, and present a 



' Cuvier, Ecch. sur les Osscm. Foss., eJ. 3, III. 8, 9, I'l. V., Fig. 1. 



