Geological Society. 385 



mical action effected in the plane of the horizon by diffused daylight 

 is greater than that exerted by direct radiation, and also that at alti- 

 tudes below J 0° direct sunlight is almost completely robbed of its 

 chemically active rays. 



GEOLOGICAL SOCIETY. 



[Continued from p. 318.] 



April 26, 1871. — Prof. Morris, Vice-President, in the Chair. 



The following communications were read : — 



1. " On a new species of Coral from the Red Crag of Waldring- 

 field." By Prof. P. Martin Duncan, M.B., E.R.S., P.G.S. 



Prof. Duncan described, under the name of Solenastrcea Prestwichi, 

 a small compound Coral obtained by Mr. A. Bell from Waldringfield, 

 and stated that it was particularly interesting as belonging to a 

 reef-forming type of corals which has persisted at least from the 

 Eocene period to the present day. The single specimen consisted of 

 several small crowded corallites, having calices from -^ to -^ inch 

 in diameter, united by a cellular epithecal ccenenchyma. It was 

 much rolled and worn before its deposition in the Red Crag, and 

 hence the author regarded it as a derivative fossil in that formation ; 

 and he stated that it probably belonged to the rich reef-building 

 coral-fauna which succeeded that of the Nummulitic period. 



2. " Notes on the Minerals of Strontian, Argyllshire." By Robert 

 H. Scott, Esq., M.A., E.R.S., P.G.S. 



The paper stated that the existing lists of minerals to be found 

 at Strontian were incorrect. The discovery of apophyllite, talc, 

 and zircon seemed to be hardly sufficiently confirmed. On the 

 other hand, Mr. Scott named several species which he had himself 

 observed in situ, and which are not noticed in any of the books, viz. : — 

 two felspars, orthoclase, and an anorthic felspar in the granite ; 

 two varieties of pyroxenic minerals in the granites and syenites, 

 neither of which have as yet been analyzed ; natrolite in the trap- 

 dykes, muscovite or margarodite in very large plates, lepidome- 

 lane and schorl. 



Specimens of these minerals and of the others found at the mines 

 were exhibited ; but it was stated that, owing to the fact that the 

 old workings at the mines in Glen Strontian had been allowed to 

 fall in, it was now no longer possible to ascertain much about the 

 association of the species. 



The one is galena, containing very little silver. The gangue is 

 remarkable for the absence of fluor and the comparative rarity of 

 blende and heavy spar. Harmotome is found principally at a 

 mine called Bell's Grove, both in the opaque variety and in the 

 clear one called morvenite. Brewsterite occurs at the mine called 

 Middle Shap ; and at the mine Whitesmith strontianite is found 

 with brewsterite, but without harmotome. Calcite is also very 

 common. 



Within the last few years a new mine has been opened, called 

 Phil. Mag. S. 4. Vol. 42. No. 281. Nov. 1871. 2 C 



