Br. C. W. Andrews — Notes on Egyptian Eocene Ifammak. 161 



the outer one of each pair being distinctly selenodont. In the first 

 molar the antero-external cusp is somewhat worn. It consists of 

 the main tubercle, which is the apex of a V of which the arms are 

 slight ridges, which rise at their ends into small tubercles ; of these 

 the anterior is situated on the anterior border of the tooth, while 

 the posterior is connected by a slight ridge with the postero-external 

 angle of the inner cusp. The postero-external cusp shows the 

 selenodont character still more plainly : its small anterior accessory 

 tubercle partly closes the main transverse valley ; the posterior 

 accessory tubercle is on the hinder border of the tooth. The internal 

 cusps are trihedral in form, so that in wear they also show a tendency 

 to a V-shaped surface, the opening of the V of the anterior cusp 

 looking backwards and outwards, that of the posterior forwards 

 and outwards. There is a slight development of the cingulum on 

 the outer side of the tooth, most marked opposite the opening of 

 the transverse valley and near the anterior end of the tooth. The 

 next molar is similar, except that on the hinder border there is 

 a minute additional tubercle lying internal to the posterior accessory 

 tubercle of the posterior cusp. In the last molar the structure is 

 similar as far as it is preserved, but the talon is almost entirely 

 wanting. 



The premolars. The anterior premolar is a compressed tooth 

 consisting of small anterior and posterior tubercles and a high main 

 cusp. In the next there is a small cingular ridge in front of the 

 tooth, and the main cusp is much larger and shows a tendency 

 towards division into an outer and an inner tubercle. In wear it 

 gives a triangular surface, from the outer angle of which a ridge 

 runs down the outer face of the tooth, while from its front angle 

 there is a small ridge connecting it with the anterior cusp, and 

 similarly posteriorly a small crest unites it with the posterior cusp. 

 The next tooth is similar, except that the posterior lobe is larger 

 and shows a tendency to give a V-shaped surface in wear. In 

 pm. 4 the division of the main cusp is complete ; the inner element 

 is small and rounded, the outer larger and V-shaped in wear. From 

 the anterior point of the V a ridge runs to the small anterior cusp,^ 

 while from the posterior a low ridge unites it with the anterior 

 limb of the V-shaped hinder lobe. To the inner side of this last 

 there is a trace of an inner cusp corresponding in position to the 

 postero-internal cusp of the molar. This remarkable mammal is 

 clearly entitled to generic distinction, and it maybe called Geniohyus 

 minis in allusion to the remarkable character of the process on its 

 mandible. 



The dimensions of the teeth in the type-specimen are : — 



pm. 1 



pm. 2 , 



pm. 3 

 pm. 4 



m. 1 ... 



m. 2 



m. 3 



DECADE Y. — VOL. I. — NO. IV. 11 



