GENIOIITUS MIRUS— GENIOIITUS FAJUMENSIS. 
195 
near tlie anterior end o£ the tooth. Tho second molar (m. 2) is similar to the first, 
except that on tlie hinder border there is an additional minute tubercle lying internal to 
tho posterior accessory tubercle of the postero-external cusp. In m. .9 the structure is 
similar, so far as it is preserved, but tho talon is almost entirely broken away. 
Tho dimensions (in centimetres) of this specimen are : — 
Extreme length so far as preserved 
Length of symphysis 
Distance between end of process and alveolar border 
"Width of sympbysial region at f. 3 
10-2 
6- 3 
7- 2 
2-5 app. 
Tho dimensions (in centimetres) of the teeth are ; — 
Length. Width. 
pm.l 1-2 -7 
jj?n. 2 1*2 ’9 
pm. 3 1 ‘3 1 
pm. 4 1‘3 I'l 
m. 1 1-5 1-1 
m. 2 1-7 1-3 
m. 3 ? 1-5 
M. 8541. Plaster cast of the above specimen. 
Made in the British Museum. 
Geniohyus fajumeiisis, Andrews. 
[Plate XIX. figs. 2, 2 a.] 
1904. Geniohyus fajumensis, C. W. Andrews, Geol. Mag. [.5] vol. i. p. 1G2. 
Type Specimen . — Portion of right ramus of mandible with the premolars well 
preserved (PI. XIX. figs. 2, 2 a); British Museum. 
This species is distinguished from G. mirus by (l)its larger size, the premolar series 
measuring 5'6 cm. in length ; (2) the main cusp being distinctly divided into an inner 
and outer tubercle in pm. 2 ; (3) the posterior lobe of the premolars being much 
larger and more distinctly selenodont. 
Form. & Loc. — ITuvio-marine beds (Upper Eocene) ; north of Birket-el-Qurun. 
M. 8435. Portion of right ramus of mandible with jvn. 1-4. Type specimen described in Geol. 
Mag. [5] vol. i. (1904) p. 162. Figured PI. XtX. figs. 2, 2 A. 
The first premolar (pm. 1) is strongly compressed, with a very small anterior tubercle, 
a high main cusp from which three ridges diverge posteriorly, one running down the 
outer face of the tooth, a second back to the anterior arm of the V-shaped posterior cusp, 
the third inwards down the inner face of the tooth. The posterior lobe is distinctly 
selenodont. In pm. 2 the anterior tubercle is larger, and the ridge running inwards 
from the main cusp has a small tubercle on its inner end. The posterior lobe is larger 
than in pm. 1. Pm. 3 has a still larger anterior tubercle and the cusp on the inner side 
of the main cusji is nearly as large as that element and clearly separated from it ; the 
posterior V is still larger. Pm. 4 is similar, except that the small anterior cusp is 
2c2 
