MCEEITHEEIUM. 99 



Suborder PROBOSCIDEA. 



Bones of skull, particularly those of the cranial region, with a strong tendency to 

 the great development of the diploe ; an alisphenoid canal ; no condylar foramen. 

 Molars lophodont, passing from a bilophodont, brachyodont type in the earliest forms 

 to a very hypsodont condition with numerous transverse crests in the later. Second 

 upper incisors enlarged to form tusks. Feet, where known, pentadactyl and digiti- 

 grade with taxeopod structure : a centrale in the carpus, at least in the young. No 

 entepicondylar foramen in the humerus. Radius and ulna, tibia and fibula complete 

 and separate from one another. No third trochanter in the femur. Astragalus 

 articulating distally with the navicular only. Calcaneum with large fibular facet. 



Family MCERITHEEIID^. 



Comparatively small animals about as large as the Tapir. Skull with greatly 

 elongated cranial region, the orbits being placed far forwards and the nares nearly 

 terminal ; probably a small proboscis was present. More than one pair of incisors 

 in upper and lower jaws : molars quadri tubercular and bilophodont. 



Genus MCERITHERITJM, Andrews. 



[Tageblatt des V. Tnternationalen Zoologen-Congresses, No. 6, p. 4, Berlin, 1901 



(Verhandlungen, p. 528).J 

 .31 3 3 



Dental formula : — i. g ; c y ; pm. ^ ; to. g. 



The second incisors in both jaws greatly enlarged and tusk-like. The last premolar 

 not bilophodont ; molars bilophodont. 



This genus is represented by several species, of which Mosritherium lyonsi is the 

 type. It is found in both the Middle and Upper Eocene deposits of the Fayum. 



Skull (PL VIII. ; PI. IX. fig. 1 ; PI. X. figs. 3, 4 ; text-fig. 40).— The following 

 description of the skull is founded mainly upon a nearly complete specimen (PI. VIII. ; 

 PI. IX. fig. 1) belonging to a young individual, in which the second incisors and third 

 molars are still uncut. This skull (C. 7867) is from the Upper Eocene beds, but does 

 not seem to diff"er in structure from the less nearly perfect specimens from the Qasr-el- 

 Sagha beds (Middle Eocene). In some cases references will be made to some of 

 these other specimens when they supply more satisfactory information on any point. 



In its general form the skull is long and somewhat depressed, with very strong and 



o2 



