RECEXTLY DISCOVERED TERTIARY VERTEBRATA OF EGYPT. 2V>7 



whole water supply of the district passes. It consists mainly of a 

 depression in the desert, the lowest portion being occupied by a large 

 lake of brackish water — the Birket-el-Qiirim — which is, in fact, the 

 remnant of the much larger body of water described by Herodotus 

 under the name Lake Mceris. From early historic times, for various 

 reasons, this lake has been decreasing in size, and there are to-day 

 nmnerous evidences of its former extent, such as traces of the old 

 shore lines marked by stimips of tamarisk bushes, which then, as now, 

 fringed its margin : but still more eloquent witnesses of its former size 

 are the ruined towns and temples now lying in the desert far from any 

 water supply. To the north of the lake the land rises in a succession 

 of escarpments separated by plains of varying width to a height of 

 about 340 meters above the sea ; the surface of the lake itself is 

 about 44 meters below the level of the ^lediterranean. The lower 

 escarpments are carved in beds of Middle Eocene age. the higher in 

 the Upper Eocene, the actual summit of the escarpments being formed 

 by the outcrop of a sheet of interbedded basalt, above which are the 

 gravelly fluvio-marine Oligocene beds which form the undulating 

 surface of the high desert stretching away toward the north. 



The vertebrate remains are found some distance to the north and 

 west of the lake, and they occur at several horizons, the lowest being 

 near the bottom of the Middle Eocene. At this horizon the beds are 

 almost exclusively marine, and the only vertebrates found are aquatic 

 types, the most interesting being a primitive toothed whale Pro- 

 zeuglodon. The next bone-bearing beds are at the top of the Middle 

 Eocene, and consist of a series of marine and estuarine deposits, 

 which contain the remains of both marine and terrestrial manunals, 

 the most important of the latter being Marithvrhim, the earliest 

 known Proboscidean, and Bari/thenum, a remarkable ungulate of 

 which the affinities are uncertain. It is. however, from the Up^^er 

 Eocene fluviatile beds that by far the greater number of forms have 

 been obtained. These beds are obviously the deposits of a great 

 river, probably flowing from the southwest, and carrying down in its 

 floods the carcasses of drowned animals inhabiting its banks, 

 together with vast numbers of tree trunks which to-day. in a silicified 

 state, are strewn over the plains formed by the dip slopes of these 

 beds. This series of fluviatile beds seems to have continued with some 

 interruptions throughout the Oligocene and ^Miocene periods, continu- 

 ing probably till well on in the Pliocene; and it is from such deposits 

 at ^logara and the T^^adi Xatrun that the Miocene and Pliocene faunas 

 above referred to are derived. In fact, the conditions seem so 

 favorable to the preservation of vertebrate remains that it is almost 

 certain that only further exploration of the region to the north of 

 the Fayiun depression is necessary to lead to the discovery of faunas 

 at other horizons. If this should prove to be the case, then it seems 



