RECENTLY DISCOVERED TERTIARY VERTEBRATA OF EGYPT. 301 



todon represents a form becoming adapted to existence on dry 

 ground. Although referred either to Mmritheriwm or Palceomasto- 

 don, several forms, intermediate both in size and in some other 

 respects betAveen these two genera, are known to have existed, but 

 the remains bv which they are represented are at present scanty. 



Pala'omastodon is represented by several species, the commonest being 

 Palceomastodon icintoni, which must have been rather larger than a 

 large cart horse. In this animal the skull approximates in man}^ 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 Moeritherium^ 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 pre- 

 molars, 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 in- 

 creased by the large procumbent incisors, corresponding to the second 

 pair of Mo^ritherium. 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, 

 Avhich (with the portion of the mandible projecting beyond the skull) 

 were covered by the fleshy upper lip and nose, the terminal portion of 

 Avhich may have been more or less free and prehensile. The limb- 

 bones are essentially similar to those of Elephas^ particularly in the 

 largest species, Palceoniastodon headnelU. The animal must have 

 much resembled in its general appearance a gigantic pig, with a short 

 neck and elongated snout. 



M (Britherium and Palceomastodon are the only genera of Probosci- 

 deans known from the Eocene beds, and at present no member of 

 the group has been found on any Oligocene strata ; but when the 

 lower Miocene beds are reached. Proboscidean remains are abundant, 

 and we find them not only in African but also in European and 

 probably Asiatic and American localities, the group having become 

 widely spread since the Upper Eocene. In the Lower Miocene 

 deposits of Europe two genera, Tetrabelodon and Dinotherimn^ are 

 found, of which only the first is at present known in Egypt, where 

 remains have been found at Mogara and in the Wadi Faregh. In 



