98 
TERTIARY VERTEBRATA OF THE FATtlM. 
'rile mandibular rarnus is massive and does not deepen so rapidly from before 
liackwards as in the other members of the "roup, 'fhe symphysis is short and 
extends to tlie level of the posterior lobe of j)m. 2. Its ventral surface is marked 
by a sli"]it prominence, behind wliich, and forming the ventral border of the mandible 
for a sliort distance, is a strong ridge for the attachment of a powerful muscle 
(1 the mandibular): the same arrangement is very Avell marked in llyrax [Procavia). 
'file 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, 
'fhe 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 llyrax [Procavia). At 
the bottom of the fossa thus formed behind the last molar, a foramen opens into a 
passage, the other aperture of which is on the inner face of the posterior portion 
of the jaw. 
C. 8818. Left maxilla with molars and premolars. Type specimen described in the Geol. Mag. 
[5] vol. i. (1904) p. 213. Figured on PI. VTT. 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 ; prn. 4, 1'7 ; 
pm. 3, 1*5; pm. 2, 1’4 ; pm. 1, I'.'i. The total length of the molar-premolar series is 
13, that of the molar series alone T'h. 
M. 8870. Plaster cast of the above specimen. 
C. 8822-3. Portions of a mandible including the greater part of the right ramus with 2-4 and 
m. 1-3, and the anterior ])ortion of the left ramus with part of the symphysis 
containing pm. 3-4, m. 1-2, and in front two incisors, probably i. 1 and i. 2. 
Figured on PI. VII. figs. 2, 3. The dimensions (in centimetres) of the teeth are : — 
Length. Width. 
VI. 3 3-3 2 
m.2 2-3 1-8 
m. 1 1-9 1-6 
pm. 4 1‘8 TO 
pm. 3 I'G 1'4 
2mi.2 1-7 1-1 
Length of series irom pm. 2-m. 3 inclusive, 12-7 cm. The widths 
of the crowns of the incisors are : i. 1, 1’4 cm. ; i. 2, ]-6 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. 
