840 MR. H. MATSUMOTO ON THE GENERA OF 



very weak, and especially so in the more posterior premolars and 

 in the molars. Mesostylar fold absent in P ' . Parastylar fold 

 of P^~^ very feeble ; that of P"* rather strong ; both parastylar 

 and mesostylar folds of M " especially strong, rounded, and 

 stout. Ridges of lower P.,— M^ W-shaped. Metaconid simple, 

 without differentiated metastylid. Posterior talon of M^ very 

 large. 



Genotype: Megalohyrax eoccenus Andrews, 1903; non Schlosser, 

 1911. 



This genus includes Megalohyrax minor Andrews, 1904; 

 Mixohyrax niloticus Schlosser, 1910; Mix. suillus Sehlosser, 

 1910 ; and Megalohyrax pyg^nce-as, sp. n., besides the genotype. 



Synopsis of Species o/ Megalohyrax. 



1-4 



(1) Extremely large species ; length of upper P 



and of M*" respectively 75 mm. and 86 mm. 

 (Andrews's type : M. 8502) eoccenus. 



1-3 



(2) Large species ; length of upper P^-* and of M 



i-espectively 63 (Andrews's type: C. 8818) — 64 

 (Am. Mus. 13332) mm. and 74 (Andrews's 

 type)— 78 (Am. Mus. 13332) mm.; that of 

 lower P _ and of M^ ^, ca. 69 (Am. Mus. 

 13345)— 70 (Sehlosser) mm. and ca. 78 (Am. 

 Mus. 13338)— 85 (Sehlosser; Am. Mus. 13345) 

 mm. respectively minor. 



(3) Rather large species ; length of upper P and 



1—3 



of M respectively ca. 54 mm. and ca. 62 mm. 

 (Schlosser's fig.) ; that of lower P and of M ^, 



55 (Sehlosser) — 57 (Sehlosser ; Am. Mus. 

 13334) mm. and 68 (Sehlosser) — 75 (Am. 

 Mus. 13334) mm., respectively . niloticus. 



(4) Small species ; length of lower P^_^ 46 mm. 



(Sehlosser) ; that of lower M^^ 32 mm. 



(Sehlosser), whereas the same measurement 

 in the immediately preceding and the next 

 species is 42 mm. and 24-25 mm. respectivelj^ . suillus. 



(5) Very small species ; length of upper P and 



of M ' respectively 35-5-36 mm. and 37 mm. 

 (type-specimen : Am. Mus. 14454) ; that of 

 lower P^_^ and of M^^, 31-5 (M. 9480)- -33 



(type-specimen) mm. and ca. 38 (Am. Mus. 



14463) — 40 (type-specimen) mm. respectively . pygmceus. 



