Geological Society of London. 31 



and South Africa, and hoped that Mr. Bauerman's future researches 

 might throw light on the ancient connexion of these continents. 



Mr. Bauerman stated in reply that he did not regard the white 

 limestone as true Chalk. He considered that the slabs showed con- 

 clusive evidence of having been chiselled by means of the flints. 



2. " On the occurrence of Celestine in the Tertiary rocks of Egypt.'' 

 By H. Bauerman, Esq., F.G.S., and C. Le Neve Foster, D.Sc, F.G.S 



This communication referred to the presence of celestine at two 

 different horizons in the Tertiary escarpment of Mokattam. The 

 beds forming the escarpment may be divided into two parts, namely, 

 the upper beds, M'-hich are brown, sandy, cellular limestones with 

 numerous oyster-beds, and the lower, or white Nummulitic lime- 

 stone proper. A bed of marl with fibrous gypsum generally occurs 

 at the junction of the two groups of strata. 



In the upper or brown beds celestine occurs with gypsum, some- 

 times in isolated crystals, but more generally in stellar or spheroidal 

 nodular aggregates, the points of the crystals being turned outwards. 

 About thirty feet lower down in the white limestone, roiigh irregu- 

 lar crystals of the same mineral are found in open hollows or druses. 

 They are often large, but much decomposed, and apjDarently crusted 

 with Nummulites, Bryozoa, &c., which are in reality included in the 

 crystals, and have become exposed by erosion. The erosion and 

 alteration of the crystals commences by the roiighening of the faces 

 of the prism, owing to the formation of numerous fine striations 

 parallel to the basal planes, and goes on frequently until the crystals 

 have entirely disappeared. The ultimate product is a hollow cast 

 of the crystal, which may then be filled with limestone, forming 

 a pseudomorph by a total replacement. This, however, appears 

 to be rare. More generally the dissolved celestine has been re- 

 deposited upon the altered crystals, forming macled groups. The 

 secondary crystals are compact, brilliant, and well formed, without 

 included foreign bodies. These phenomena were attributed by the 

 authors to the solubility of sulphate of strontia in chloride of sodium. 



3. "Note on the Echinodermata, bivalve Mollusca, and some 

 other Fossils from the Cretaceous Eocks of Sinai. " By Dr. P. 

 Martin Duncan, F.E.S., Sec. G.S., &c. 



The author identified the fossils brought by Mr. Bauerman from 

 Sinai as belonging to the Upper Greensand and Hippuritic Chalk 

 horizons, and correlated them with those of Algeria and South- 

 eastern Arabia. He determined the following species : — 



Seterodiadema Libycum, Ag. & Desor, sp. 

 Discoidea subucula, Klein. 

 Forguemolli, H. Coq. 



lEpiaster distinctus, Agass. 



tumidus, Desor. 



Feriaster ohlongtis, D'Orb. 

 Hemiaster Ceiioinancnsis, Cotteau. 

 Phymosoina Delmarrei, Desor. 

 Fseudodiadema variolare, Brongn. 

 Fediiwpsis, sp. 

 Flicatula Fourneti, H. Coq. 

 Fecten asper, Lam. 

 l^eilAia alpina, D'Orb. 



Neitliia tricostata, Boyle. 

 Exogyra plicata, Goldfuss. 

 Ostrea Aiiressensis, H. Coq. 



, var. major, nobis. 



Mermeti, H. Coq. 



Exogyra Ovenvegi, von Bucb, 

 Ostrea Delattrei, H. Coq. 



curvirostris, Nilss. 



Caprotina Toucasiann, D'Orb. 



sttbcequalis, D'Orb. 



Archiacianus, D'Orb. 



Fadiolites, sp. 

 Glavagella, sp. 



