EGYPTIAN TERTIARY VERTEBRATA 675 



adapted to existence on dry ground. Although referred either 

 to Mceritherinm or Palceomastodon, several forms, intermediate 

 both in size and in some other respects between these two 

 genera, are known to have existed, but the remains by which 

 they are represented are at present scanty. 



Palceomastodon is represented by several species, the com- 

 monest being P. wintoni, which must have been rather larger 

 than a large cart-horse. In this animal the skull approximates 

 in many respects to that of the Elephants proper. Thus the 

 nostrils have shifted back till they are only a little in advance 

 of the orbits, and the nasal bones are very short. At the same 

 time the bones at the back of the skull are much more enlarged 

 than in Mceritherinm, owing to the increased development of 

 spongy tissue within them. The upper incisors are now 

 reduced to a single pair, the second, and form moderately 

 large downwardly directed tusks, with a band of enamel on 

 their outer side. The canines have disappeared. There are 

 three upper premolars, the last having a pair of transverse 

 ridges, while the molars have three transverse crests. The 

 mandible is in many respects peculiar ; the anterior spout-like 

 portion is greatly prolonged, so that it projected considerably 

 beyond ,the skull, and its extension is increased by the large 

 procumbent incisors, corresponding to the second pair of 

 Moeritherium. The other incisors, the canine, and the first two 

 premolars have disappeared, and there is a long edentulous 

 interval between the tusks and the third premolars. The 

 fourth premolar is two-ridged, the first and second molars 

 three-ridged, while in the third molar there may be as many 

 as four transverse crests. The neck was a little longer than 

 in the Elephants, and the animal could doubtless reach the 

 ground with its lower incisors, which (with the portion of the 

 mandible projecting beyond the skull) were covered by the fleshy 

 upper lip and nose, the terminal portion of which may have 

 been more or less free and prehensile. The limb-bones are 

 essentially similar to those of Elephas, particularly in the largest 

 species, P. beadnelli. The animal must have much resembled 

 in its general appearance a gigantic pig, with a short neck and 

 elongated snout. 



Moeritherium and Palceomastodon are the only genera of 

 Proboscideans known from the Eocene beds, and at present no 

 member of the group has been found on any Oligocene strata ; 



