GENIOHTrS MIEUS. — GENIOHTTJS FAJUMENSIS. 195 



near the anterior end o£ the tooth. The second molar (m. 2) is similar to the first, 

 except that on the hinder border there is an additional minute tubercle lying internal to 

 the posterior accessory tubercle of the postero-external cusp. In m. 3 the structure is 

 similar, so far as it is preserved, but the talon is almost entirely broken away. 

 The dimensions (in centimetres) of this specimen are : — 



Extreme length so far as preserved 16'2 



Length of symphysis 6-3 



Distance between end of process and alveolar border . . . 7'2 

 Width of sympbysial region at i. 3 2 '5 app. 



The dimensions (in centimetres) of the teeth are : — 



Length. Width. 



pm.l 1-2 -7 



pm.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 fajumensis, Andrews. 



[Plate XIX. figs. 2, 2 A.J 

 1904. Geniohyus fajumensis, C. W. Andrews, Geol. Mag. [5] vol. i. p. 162. 



Type Specimen. — Portion of right ramus of mandible with the premolars well 

 preserved (PL XIX. figs. 2, 2 a); British Museum. 



This species is distinguished from G. mirus by (1) 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. & Log. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. 



M. 8435. Portion of right ramus of mandible with pm. 1-4. Type specimen described in Greol. 

 Mag. [5] vol. i. (1904) p. 162. Figured PI, XIX. 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 pni. 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 cusp 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 



