392 Geological Society. 



January 18th. — J. E. Marr, Sc.D., F.R.S., President, 

 in the Chair. 



The following communication was read : — 



'On the Geology of Arenig Fawr and Moel Llyfnant.' By 

 William George Fearnsides, M.A., F.G.S. 



This paper contains a detailed description of the succession of 

 beds in Sedgwick's typical area of development of his Arenig 

 Series. The following beds are described : — 



Orthis-lAvbQstcme. 



Thin ashy shales. 



Upper ashes of Arenig and Llyfnant. 



Daerfawr Shales, with a few graptolites, apparently of the Didymograptus- 



Murchisoni Zone. 

 Upper platy ashes, passing down into : — . 

 Agglomerate. 

 Lower platy ashes. 

 Didymograptus-bifidm Beds: blue shales with occasional ashes, passing 



clown into : — 

 Didymograptm-hinmdo Beds : dark calcareous shales, with some ashes. 

 Calymene-A.sh.es, with some calcareous material and occasional shaly beds. 

 Didymograptus-extensus Flags : quartzose flags with shaly partings. 

 Basal grit. 



Unconformity; 



Shumardia-^ha\.es, passing down into : — 

 Asaphe ^<s-Flags. 



Hellerophon-Beds : hard shales, with Parabolinella triarthrus in the upper 

 part. 



^2-Bedr BaUd ' } not wel1 ex P° SecL 



Peltura-Beds : Peltura scarabaoides abundant in the middle part. These 



are separated by thin beds with Orthis lentieularis from : — 

 Parabclina-Be&s, with P. spimdosa. 

 Lingida-~Beds, with Lwgulella Davisil. 



The unconformity marks the base of the Arenig Series. The 

 0r£7m-Limestone yields Lower Caradoc-Sandstone forms, and dips 

 beneath the great Black-Shale Series, which occupies the adjoining 

 belt of country. 



The author discusses the relationship of these divisions to 

 corresponding beds of other areas. He gives a description of 

 the intrusive igneous rocks, and some account of the structure 

 of the district and the nature of its glaciation. 



February 1st..— J. E. Marr, Sc.D., F.R.S., President, 

 in the Chair. 



The following communication was read :— 



' On the Sporangium-like Organs of Glossopteris Browniana, 

 Brongn." ByE. A. Newell Arber, M.A., F.L.S., F.G.S. 



