586 PROF. J. W. GREGORY ON [Nov. I9H, 



base. The upper part of that wadi is a deep ravine, cut by the 

 recession of a waterfall which exists only in the rainy season. 

 Above the fall the valley continues as a wide dale, on the floor of 

 which are exposures of the limestone that overlies the nodular seam 

 of the Fountain of Apollo. The Cyrene Limestones extend for 

 about 2 miles to the south, and then, after crossing a flat-floored 

 valley covered with a sheet of alluvium about a mile in length, the 

 ground rises to scrub-covered hills of the hard Slonta Limestones. 

 The Echinolampas Bed occurs at a well known as Bir-Hu, at the 

 height of 2020 feet. The country is intersected by a series of deep 

 ravines, and water must be more easily obtained here than in most 

 parts of Cyrenaica. About a mile south of Bir-Hu is a ridge capped 

 by the Cyrene Limestones, and on the lower ground to the south 

 the rough-weathering hummccky limestone containing casts of 

 shells and Ecliinolampas crops out at Gaafs-a-mudi. At the height 

 of 2200 feet in the Wadi Firyah, above the horizon of the Ecliino- 

 lampas Bed, is a limestone full of reef-building corals. A little 

 farther south, at the height of 2470 feet, we crossed the divide be- 

 tween those streams the beds of which descend northwards through 

 the Wadi Firyah and those that begin their course southwards in 

 the direction of Slonta. At the height of 2350 feet is a well, in 

 which the water is upheld by a laminated sandy limestone con- 

 taining flattened stems like that at Ain Sciahat. It yields many 

 shell-fragments. The limestone above it yields the same pectens 

 as at Ain Sciahat, and also Ostrea crassicostata G. B. Sow. ; it is 

 evident, therefore, that the beds are of Aquitanian age. 



This outlier of the Cyrene Limestones is about 3 miles wide, and 

 it is succeeded on the south by the nummulitic Slonta Limestones, 

 which are much harder and weather brown. They contain, as 

 below Ain Sciahat, N. gizehensis var. lyelli, and many specimens of 

 JSf. curvispira, the latter of which, however, occurs also in the Derna 

 Limestones. I did not see the coral-limestones which usually mark 

 the upper bed of the Slonta Series, probably owing to the enforced 

 quickness of our march. The Slonta Limestones here form open 

 treeless downs extending as far southwards as we could see. The 

 Echinolampas Bed occurs on the summit of some of the hills near 

 a conspicuous landmark, the shrine of Sidi Mahomet Mahridi, as 

 also at the old Boman cisterns near Slonta. 



A few Arabs were living at Slonta, and I endeavoured from them 

 to learn the nature of the country farther south. North of the shrine 

 of Sidi Mahomet Mahridi we had crossed a slight ridge at the height 

 of 2600 feet above sea-level ; the well at Slonta is at 2400 feet, 

 and the country apparently has a long gradual slope southwards. 

 According to the sketch-maps of this district, the Cyrenaican plateau 

 descends to the Siwa-Aujela depression in two abrupt steps. But, 

 according to the Arabs, the plateau sinks gradually into the plains 

 to the south. 



