106 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Noy. 3, 
The upper molar teeth in other mammalia, with which the one 
above-described may be compared, are those of the Cheropotamus * 
and Anthracotherium of Cuvier +, and also those of the genera Di- 
chodon t and Hyracotherium§. 
The teeth of the typical Anthracotherium (Anthr. magnum) 
described and figured by the great Anatomist in his immortal 
‘Qssemens Fossiles,’ are the same (second and third true molars, 
left side, upper jaw) as those here compared, which are the only 
complete upper molars in the series of the remains of the present 
species (Hyopotamus bovinus) obtamed by Lady Hastings. I shall 
begin the comparison, however, with the molars of the Chero- 
potamus, of which fortunately a beautiful cast of the upper jaw 
described by Cuvier exists in the Museum of the Royal College of 
Surgeons. In the upper true molars of this genus, the fifth lobe 
(p) is so situated and developed as to appear like one of the four 
normal lobes; the internal and anterior normal lobe 7 being pro- 
portionally reduced so as to appear like a mere accessory tubercle : 
the crown also presents a sixth still smaller lobe or tubercle be- 
tween the two posterior principal lobes; of this there is no trace 
in Hyopotamus. The middle of the deep transverse valley is not 
interrupted in Hyopotamus as in Cheropotamus by any tubercle: 
a slight ridge extends from it to the interspace between the antero- 
external (0) and the antero-median (7) lobe: i Cheropotamus there 
rises an irregular, slightly bifid tubercle at this part. The whole 
base of the crown of the tooth in Cheropotamus is git by a ridge, 
which rises into tubercles at different parts||. In Hyopotamus the 
‘cingulum,’ or basal ridge is limited to the anterior and posterior 
parts of the base of the crown ; and there is no tubercle between the 
two inner lobes. The lobes of the molar of the Hyopotamus are 
loftier, and with sharper summits and sharper anterior and posterior 
angles; the longitudinal rismg at the middle of the outer sides of the 
two outer lobes is much more developed in Cheropotamus: the bulging 
or prominence at the outside of the interspace between those lobes 
(‘ vers le milieu du bord externe,” Cuv.) is, on the other hand, much 
larger and more prominent in Hyopotamus. | 
If we next compare the penultimate upper left molar of Hyopota- 
mus with the homologous tooth in Anthracotherium, we shall find 
that, although the anterior internal lobe z is indicated in Cuvier’s 
figure, and in that copied from M. de Blainville’s ‘Ostéographie,’ in 
Pl. VII. fig. 9, m 2 and m 3, between the two larger anterior lobes, it 
is comparatively so little developed that Cuvier omits to mention it, 
and says, “la pénultiéme molaire ne porte que quatre pointes.” In 
the external protuberance from the basal interspace between the two 
external lobes, and in the curve formed upon it by the uniting oppo- 
* Ossemens Fossiles, 4to, t. iii. p. 262, pl. 68. fig. 1 (the penultimate molar, 
left side). 
+ Ib. p. 399, pl. 80. fig. 1 (same molar). t Quart. Geol. Journ. vol. iv. pl. 4. 
§ British Fossil Mammalia, figs. 166, 170, pp. 422, 424. 
|| ‘‘ Enfin, toute la dent est entourée d’un collet quis’éléve lui-méme en tubercules 
4 l’angle antérieur externe, et vers le milieu du bord externe.” (Cuvier, /. ec. p. 263.) 
