Dr. P. M. Duncan on Echinodermata, §c. of Sinai. 163 



the upper beds, which 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, rough irregular 

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

 They are often large, but much decomposed, and apparently 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 roughening of the 

 faces of the prism, owing to the formation of numerous fine stria- 

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

 entire disappearance of the crystals. The ultimate product is a 

 hollow cast of the crystal, which may then be filled with limestone, 

 forming a pseudomorph by total replacement. This, however, ap- 

 pears to be rare. More generally the dissolved celestine has been 

 redeposited 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 Rocks of Sinai." By Dr. P. Martin 

 Duncan, F.R.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 : — 



Neithia tricostata, Bayle. 

 Exogyra plicata, Golclfuss. 

 Ostrea Auressensis, H. Coq. 



, var. major, Dune. 



Mermeti, H. Coq. 



Exogyra Overwegi, von Buck. 

 Ostrea Delattrei, H. Coq. 



curvirostris, Nihs. 



Caprotina Toucasiana, Z>' Orb. 



subffiqualis, D 1 Orb. 



Archiacianus, D Orb. 



Radiolites, sp. 

 Clavagella, sp. 



Heterodiadema Libycurn, Ag. $ Desor, 



sp._ 

 Discoidea subucula, Klein. 



Eorguemolli, H. Coq. 



Epiaster distinctus, Agass. 



tumidus, Desor. 



Periaster oblongus, D' Orb. 

 Hemiaster Cenomanensis, Cotteau. 

 Phymosorna Delmarrei, Desor. 

 Pseudodiaderaa variolare, Brongn. 

 Pedinopsis, sp. 

 Plicatula Fourneli, H. Coq. 

 Pecten asper, Lam. 

 Neitbia alpina, D' Orb. 



4. " On the Existence during the Quaternary Period of a Glacier 

 of the Second Order, occupying the ' cirque ' of the valley of Palheres 

 in the western part of the granitic ' massif of the Lozere." By M. 

 C. Martins, For. Corr. G.S. 



After mentioning that no one had satisfactorily proved the former 

 existence of glaciers in the Puys of Auvergne, the Cevennes moun- 

 tains, or the massif of the Lozere, the author stated that, from study- 

 ing the Government map, it occurred to him that traces of a glacier 

 qught to be found in the eastern part of the granitic massif of the 



M2 



