98 
TEKTIARY VERTEBRATA OF THE FAYOM. 
The mandibular ramus is massive and does not deepen so rapidly from before 
backwards as in the other members of the group. The symphysis is short and 
extends to the level of the posterior lobe of 2 )m. 2. Its ventral surface is marked 
by a slight prominence, behind which, and forming the ventral border of the mandible 
for a short distance, is a strong ridge for the attachment of a powerful muscle 
(1 the mandibular) : the same arrangement is very well marked in Ilijrax {Procavia). 
'I'lie ascending ramus is broad ; its inner border is formed by a ridge continuous with 
the alveolar border, while the outer rises on the outer face of the ramus beneath m. 3. 
The inner border, about 3 cm. above the talon of m. 3, turns sharply outwards and 
joins the outer border to form the thin anterior edge of the coronoid process: exactly 
the same arrangement may be seen in the mandible of Ihjrax {Procavia). At 
the bottom of the fossa thus formed behind the last molar, a foramen opens into a 
])assage, the other aperture of which is on the inner face of the posterior portion 
of the jaw. 
C. 8818. Left maxilla with molar.s and premolars. Type specimen described in the Geol. Mag. 
[5] vol. i. (1904) p. 213. Figured on PI. VII. fig. 1. The dimensions (in centi- 
metres) of the specimen are : length of m. 3, 2'9 ; m. 2, 2'G ; m. 1, 2’1 ; fm. 4, 1'7 ; 
pm. 3, 1’5; pm. 2, 1’4 ; pm. 1, 1%5. The total length of the molar-premolar series is 
13, that of the molar series alone 7'5. 
>1. 8870. Plaster cast of the above specimen. 
C. 8822-3. Portions of a mandible including the greater part of the right ramus with pm. 2-4 and 
m. 1-3, and the anterior portion of the left ramus with part of the symphysis 
containing pm. 3-4, m. 1-2, and in front tw'o incisors, probably i. 1 and i. 2. 
Figured on PI. VII. figs. 2, 3. The dimensions (in centimetres) of the teeth are ; — 
Length. Width. 
m.3 3‘3 2 
m.2 2-3 1-8 
m. 1 1-9 1-6 
pm. i 1‘8 I’G 
pm. 3 l‘(5 1-4 
pm. 2 1'7 IT 
Lengtli of series from pm. 2-m. 3 inclusive, 12-7 cm. The widths 
of the crowns of the incisors are : i. 1, IT cm. ; i.2, PG cm. 
M. 8871. Plaster casts of the above specimens. 
M. 9220. Left ramus of mandible with m. 2-3, pm. 3, and part of pm. 4. 
