1 5 2 Geological Society. 



schists dip uniformly to jST.E., the limestone dips in a very variable 

 manner E.S.E., E., and but rarely N.E., any dip N. of E. being ex- 

 ceptional and then only at a distance from the schist. Again, the 

 Sinoo mass of limestone, cut off from the Durness area by a faulted 

 strip of gneiss, dips either E.S.E., or even more to S. After discuss- 

 ing the relation of the quartzite and^ gneisses, the author passed to 

 the Assynt district, and pointed out that the relations of the 

 limestone and the quartzite are by no means satisfactorily established, 

 that their conformity is rendered dubious by a marked discordance 

 of strike, and that the limestone lies in a synclinal basin, so that 

 its dip in one place is in the opposite direction to that of the 

 quartzite. Erom the above considerations the author holds that in 

 these districts there is no proof of the Lower-Silurian age of the 

 quartzite and newer series of flaggy gneiss and schist. 



3. " On a Boulder of Hornblende-Pikrite near Pen-y-Carnisiog, 

 Anglesey." By Prof. T. G. Bonney, M.A., F.R.S., Sec.G.S. 



The boulder described had been originally about a cubic yard in 

 volume ; and the fragments lay in a field to the left of the road from 

 Pen-y-Carnisiog to Bwlyn. The ground-mass consists of hornblende 

 and serpentinous products, with a little mica. In this are crystals, often 

 -| inch long, of brown hornblende with enclosures of altered olivine. 

 The author doubted whether this hornblende is not a paramorph after 

 augite ; some of that in the ground-mass is certainly of secondary 

 origin. He compared the rock with a pikrite from the Lleyn penin- 

 sula and two described by Prof. Geikie from Eifeshire. It differs 

 from all these, but has a singular resemblance to a pikrite from 

 Schriesheim (Odenwald), except that it is rather more altered. He 

 called attention to the rock in hopes that some geologists may dis- 

 cover it in situ, as it will be of much value in deciding in what 

 direction the ice has moved over Anglesey. 



January 19, 1881.— Robert Etheridge, Esq., F.R.S., 

 President, in the Chair. 



The following communications were read : — 



1. " Further Notes on the Family Diastoporidse, Busk." By G. E. 

 Vine, Esq. Communicated by Prof. P. Martin Duncan, M.B. Lond., 

 F.R.S., F.G.S. 



2. " Further Notes on the Carboniferous Fenestellidae." By G. 

 W. Shrubsole, Esq., F.G.S. 



