192 
TERTIAEY VEETEBEATA OF THE FAYtM. 
and are separated both from the incisors "and premolars by long diastemata. In the 
ni)pcrja\v there are four premolars, 1 being separated from 2 by a diastema. 
'I'he molars have very brachyodont crowns, the cusps being only slightly selenodont 
but strongly convex on their outer face. The type species is R. valdense. Later, 
Kowalevsky * described and figured another species, B. fronstettense, in which the 
upper molars are still more bunodont, the cusps being shorter and thicker; the 
middle fold of the outer wall [mesostyle) is also more strongly developed, as, judging 
from the figures, is the cingulum generally. A single tooth from the Upper Eocene 
of the Fayum resembles those figured by Kowalevsky so closely in its structure that 
it is here referred to the same genus, though, on account of its much greater size, to 
a distinct species. 
Rliagatlierium aegyptiacum, sp. nov. 
[Plate XVIII. fig. 5.] 
Type Specimen. — Left upper molar, probably the third (PL XVIII. fig. 5); British 
Museum. 
The tooth upon which this species is founded is clearly that of a primitive 
Anthracotheroid, in which the selenodont condition of the molars of the later forms 
is still only indicated, and the cusps are low and strongly convex on the outer as well 
as on the inner face. There are three main cusps in front and two behind, as usual 
in the family ; the intermediate anterior cusp is the smallest. The cingulum is well 
developed round the whole crowm, with the exception of the outer face of the 
})ostero-cxternal cusp. The fold on the outer face between the main cusps forms 
a w’cll-developed mesostyle. In wear, the inner cusps would tend to give a V-shaped 
pattern, but this would not be the case with the outer ones. The tooth differs from 
those of B. valdeme, Pictet, and B. fronstettense, Kowalevsky, by its much larger 
size, and from the former by its still more bunodont crown. Possibly, wdien the 
dentition is fully known, it may be necessary to establish a new genus for this species. 
Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-et-Qurun. 
M. 8449. Left upper molar, probably the third ; the low cusps are Just coming into wear. Type 
specimen, figured PI. XVIII. fig. .5. The length of this tootli is 1'8 cm.; its greatest 
width 2 cm. In 11. va/den.'^e the corresponding measurements are ‘75 cm. and ’8 cm.; 
in IL fronstetlense they are 1 cm. and 1 cm. 
*■ “ Monographie der Gattuug Anthmcolherium, Cuv.,'’ rala.'outograpliica, vob xxii. (1876) p. 228, pi. viii. 
figs. 57, 58. 
