FOSSIL HYBACOIDS FROM THE FAYI>M. 841 



(1) Megalohyrax eoc.4:nus Andrews. 



M. eoccenus Andrews, Geol. Mag,, Decade iv. a^oI. x. 1903, 

 p. 340, text-fig. 1 ; Andrews, Brit. Mus. Cat. Tert. Vert. Fayiun, 

 Egj^pt, 1906, p. 92, pi. vi. figs. 1 & 2 \non text-fig. 39). 



M. 8502 ; type-specimen ; fragment of right premaxilla and 

 maxilla, bearing C — M in situ. 



Schlosser has failed to undei-stand this type-specimen, hence 

 algo to identify this species and this genus. He had the opinion 

 that the teeth of this specimen, as figured by Andrews, were 

 erroneously restored. According to my actual observation of 

 this specimen, Andrews's illustration proves to be fundamentally 

 correct, though the measurements of the teeth of this specimen 

 were confusingly misprinted (width as " length," and length as 



"width" in P" — M'). The more important dental characters 

 of this specimen are:— (1) The premolars have no proper 

 mesostyle (a distinctive character from Titanohyra,v), though 



the external basal cingulum of P" (unknown in P ) has a 

 raised tubercle just outside the metacone. (2) The parastylar 

 and mesostylai- folds of the molars are very strong, rounded, and 

 stout (a distinctive character fi'om Titanoliyrax). (3) The para- 

 conal and metaconal folds of the molars are exceedingly feeble 

 and i)isignificant (a distinctive character from Geniohyus and 



Bmiohyrax). (4) The P " have no hypocone ; P", a very rudi- 

 mentary one ; and P , a more or less well-developed one (in 

 Geniohyus and Bunohyrax, all P have no hypocone ; in certain 

 other species of Megalohyrax, P have no hj^pocone and P has 



1-4 



one ; and in Titanohyrax, all P have a well-developed hypo- 

 cone). (5) The posterior surface of the protocone of P — M 

 is not rounded, but is provided with a well-rounded ridge ; the 



1—3 



anterior inner surface of the hypocone of M is not rounded, 

 but is provided with a well-developed metaloph, which is as 

 strong as or even stronger than the ridge on the posterior surface 

 of the same cone (distinctive characters from Titanohyrax). 

 (6) The surface of enamel of the teeth is not smooth, but very 

 rough (a distinctive character from Titanohyrax). These 

 characters indicate that Megalohyrax typified by this specimen 

 does not correspond to Schlosser's '"'' Megalohyrax'''' (= Titanohyrax) 

 at all, but to his '•'• Mixohyrax''' { = Megalohyrax). 



As Andrews's measurements of the teeth of this specimen were 

 confusingly misprinted, I here give the measurements taken by 

 me (in mm.) : — 



