94 Re2)orts and Proceediiujs — Mineralogical Society. 



Ill-preserved specimens of Monngraptus vomeriiius, found in the highest 

 Silurian strata exposed, show that these are of Wenlock age. 



Probably in early post-Silatian times occurred the intrusions of 

 keratophyi-e and labradorite-porphyrite which are met with at, or near, 

 the base of the Silurian. Then followed a period of important earth- 

 movement, connected in all probability with the Caledonian movements 

 in otlier regions. The area was folded into a syncline, the axis of 

 which ran roughly north-east and south-west; and, perhaps owing to 

 the rigid mass of felsite in the northern part of the peninsula, the 

 Silurian rocks in adjusting themselves became traversed by numerous 

 cross-faults. At some latter period intrusions took place of numerous 

 small dykes and sills of dolerite. 



Dr. Henry Woodward, F. U.S., supplies an Appendix giving a 

 description of a new species of Caryocaris (C. kilhridensis). 



II, — Mineralogical Society. 



Anniversary Meeting, November 14, 1911. — Professor W. J. Lewis, 

 F.R.S., President, in the Chair. 

 R. H. Solly : Dufrenoysite, associated with seligmannite from the 

 Binnental. In a small cavity, discovered in August, 1911, in the 

 dolomite rock in the Lengenbach Quarry, were a few brilliant crystals 

 of dufrenoysite, coated on their fractured surfaces with minute crystals 

 of seligmannite. Measurements of two crystals of the former led to 

 the discovery of twenty-six new forms. — H. G. Smith : A simple 

 graphic method for determining extinction angles in sections of 

 biaxial crystals. A means of drawing a crystal projected on any 

 plane and finding the extinction directions was explained. — Dr. G. T. 

 Prior: On the Meteoric Stone which recently fell in Egypt. A meteorite 

 fell on June 29, 1911, near the village of Abdel Malek, about 

 44 km. E.S.E. of Alexandria. It exhibits a brilliant, varnish-like 

 crust, and consists mainly of a coarse-grained crystalline aggregate, 

 without chondrules, of a green pyroxene, and a brown ferriferous 

 olivine, with only a little felspar and practically no nickeliferous iron. 

 A quantitative analysis showed that the stone included a high per- 

 centage of lime, and that the green pyroxene, containing much lime 

 as well as ferrous oxide and magnesia, constitutes about three- 

 quarters of the stone by weight. A study of thin sections under the 

 microscope showed that the pyroxene is generally twinned on 100, 

 gives extinction angles as high as 35°, and exhibits ' herring-bone ' 

 structure owing to fine twinning on 001. — T. Crook and S. J. 

 Johnstone: Striiverite from the Federated Malay States. A mineral 

 of doubtful identity found in the course of tin-raining on the 

 Sebantun Iliver, Kuala Kangsar district, Perak, was proved to be 

 striiverite ; it closcdy resembles the mineral recently recorded by Hess 

 and Wells from South Dakota, U.S.A.— A. Hutchinson: On the 

 temperature at which gypsum becomes o])tically uniaxial. A small 

 plate of gypsum, cut normal to the acute bisectrix, was placed in 

 a glass-topped cell, through which a stream of water at a determinate 

 temperature was passed, and the optic picture was studied under 



