Dr. C. W. Andrews — Expedition to the Fayum, Egypt. 341 



of a single low cusp, on the inner side of wliich there is a fairly 

 well -developed cingulum. There is no distinct alveolus for the 

 third incisor immediately in front of the canine, as in Saghatlierium 

 (Fig. 2).i 



Comparison of the dentition just described with that of the much 

 smaller SagJiatherium antiquum shows that in nearly all important 

 points in the structure of the teeth the two agree; on the other 

 hand, the absence of the incisor in front of the canine, as well as the 

 much greater size, seem to justify the generic separation of this 

 species, for which the name Megalohyrax eocmnus is proposed. 



The discovery of this large Hyracoid throws much light on 

 several doubtful fragments previously collected by Mr. Beadnell or 

 myself. For instance, there is little doubt that the remarkable 

 premaxilla bearing a long pointed tusk, triangular in section, 

 provisionally referred to PJiiomia in the paper above cited, belongs 

 to the present species, and in the figure I have had it sketched in 

 in outline to show its probable position with regard to the maxilla 

 here described (Fig. 1). The reason for adopting this view is that in 



Fig, 3. 



-Right ramus of mandible of Pterodon africamis, sp.n. s marks posterior 

 end of symphysis. One-third nat. size. 



a specimen of the upper dentition (Fig. 2) of Saghatheriam antiquum 

 in the British Museum the front of the premaxilla is occupied 

 by a precisely similar tusk-like incisor {i.) ; and since, as already 

 mentioned, the molars of this species are closely similar to those of 

 Megalohyrax eoccenus, it is at least probable that the latter also possessed 

 a similar tusk, a supposition fully confirmed by the occurrence in 

 the same beds of the remarkable specimen referred to, which 

 corresponds both in size and form to what might be expected to 

 have existed. It should be noted that these tusk-like incisors, 

 both in shape and in the arrangement of the enamel, agree closely 

 with those of Procavia dorsalis,^ and it is a very remarkable fact 

 that this peculiar specialisation of the incisors in the Hyracoidea had 

 already arisen in the Upper Eocene. 



1 " A Preliminary Note on some New Mammals from the Upper Eocene of 

 Egypt," by C. W. Audi-ews & H. J. L. Beadnell, Cairo, 1902. 



2 That is to say, that the tooth is long, curved, and grows from a persistent pulp ; 

 in section it is triangular, one of the angles being anterior. The two anterior faces 

 only are enamel covered, and the tooth Avears to a sharp point. 



