F. Chapman — Foraminiferal Limestones from Egypt. 63 



No. 2,195, Ih. " Heterostegina-WvaQBioTieB, 2 kilometres north-west of 

 Camp 49, Wadi Dara, east of Eed Sea Hills. Outlier of Miocene 

 on Eocene and Cretaceous " (T. Barron). (PI. IV, Fig. 1.) 



An ochreous limestone, partly dolomitic. The interstitial material 

 originally calcitic, but now largely replaced by minute rhombohedral 

 crystals of dolomite. A few subangular and rounded quartz-grains 

 also occur in this rock, the larger ones exhibiting a coarse poly- 

 synthetic structure under polarized light, such as may be seen in 

 fragments derived from secondary quartz-veins. 



The Helerostegmce have been subjected to some considerable 

 amount of pressure and are more or less deformed ; the thin 

 discoidal tests are often bent, and occasionally fractured over and 

 against the larger quartz-grains. The tests of Heterostegina depressa 

 constitute a large proportion of the limestone, perhaps as much as 

 90 per cent. Associated with the Heterostegina we notice many 

 specimens of Amphistegina Lessonii, and in one section of the rock 

 a crushed specimen of Alveolina was noted, presumably derived. 

 Besides the foraminifera, there are several sections of polyzoa and 

 some traces of lamellibranch shells. 



Miocene. 



No. 1,622, 5Qh, and No. 1,622, 6h. " Limestone under Eocene nodular 

 bed near Jebel Hamrawein " (T. Barron). (PI. IV, Fig. 2.) 



This limestone contains a large proportion of a small variety of 

 N. curvispira. There are apparently no other organisms present 

 in the rock. The groundmass of this limestone is well crystallized, 

 and contains numerous brown, indefinite-shaped glauconite grains. 

 The specimen 567i contains nodules of chert which show a gradual 

 passage from the limestone into the chert, the latter being iso- 

 morphous with the former as regards the organic contents. In 

 the passage zone between the limestone and the chert a great deal 

 of dolomite is present in the form of small rhombohedral crystals. 

 In connection with these facts it is worth noting similar occurrences 

 in many of the Devonian and Carboniferous cherts of England, and 

 it seeins to point to a certain sequence of chemical changes which 

 occur in the silicification of limestones. 



Middle Eocene : Mokattam Series. 



No. 3,535, 521. " Nummulitic limestones with bryozoa. Corner 

 of cliff north of Salamuni, between Assiut and Qena, east side 

 of Nile " (H. J. L. Beadnell). (PI. IV, Fig. 3.) 



A pure white chalky or earthy limestone with many nummulites, 

 both large and small, and some Operculince. The groundmass of 

 this rock is very finely crystalline, and was most probably a chalky 

 mud in its original condition. It contains Operculina complanata 

 var. pyramidiim, Nummidiies Beaumonti, and N. siib-Beaumonti. 



Eocene : Upper Libyan or Lower Mokattam Series.^ 



_^ The fauna of this and the following specimens appears to be homotaxial in part 

 ■with the Lower Mokattam beds found farther to the north, and this view is shared by 

 Mr. Beadnell, who has written to me on the subject in a letter dated 6th April, 1901. 



