Eozoic and Pahvozoic Rocks of the Coast of Canada. 233 



included plates of biotite, and over 12 per. cent, of magnetic iron-ore. 

 It is to the presence of the last-mentioned mineral that the zonal 

 portion owes its dark colour. By means of a Sonstadt's solution the 

 oligoclase was isolated and analyzed with the following results : — 



SiO a 



= 



60-99 



A1,0 3 



= 



25-56 



CaO 



= 



4-88 



Na a O 



= 



7-73* 



Loss on ignition 



= 



•84 



100-00 

 Sp. Gr. = 2-640 

 This is the composition of an oligoclasc of the formula Ab 3 An. 



The felspar of the zonal portion is disposed radially, the iron-ore 

 radially and concentrically, while the mica appears to obey no fixed 

 law of arrangement. 



A synopsis of the literature concerning the occurrence of similar 

 concretionary bodies in granite was then given, the following authors 

 being referred to : — Leopold v. Buch, Gustav Rose, Allnaud, Char- 

 pentier, Jokely, von Andrian, Zirkel, G. W. Hawes, M. de Kronst- 

 schoff, J. A. Phillips, vom Bath, Eouque, Halst, Brogger, and 

 Backstrom. 



The conclusion the author arrived at from a consideration of the 

 subject was, that concretionary bodies occurring in granite, may, 

 according to the mode of arrangement of their constituents, be 

 divided into three classes, viz. : — 



1. The concretionary patches of Phillips. 



2. The granospherites of Vogelsang. 



3. The belonospherites of Vogelsang. 



The Spheroids from Mullaghderg belong to the last-mentioned 

 class. They must be regarded as concretions formed, during the 

 consolidation of the granite magma, by a process of zonal and radial 

 crystallization around an earlier-formed nucleus. 



2. " On the Skeleton of a Sauropterygian from the Oxford Clay, 

 near Bedford." By B. Lydekker, Esq.*, B.A., F.G.S. 



3. " On the Eozoic and Palaeozoic Rocks of the Atlantic Coast of 

 Canada in comparison with those of "Western Europe and the 

 Interior of America." By Sir J. W. Dawson, LL.D., F.RS., F.G.S. 



The author referred to the fact that since 1845 he had con- 

 tributed to the Proceedings of the Geological Societv a number of 

 papers on the geology of the eastern maritime provinces of Canada, 

 and it seemed useful now to sum up the geology of the older forma- 

 tions and make such corrections and comparisons as seemed war- 

 ranted by the new facts obtained by himself, and by other observers 

 of whom mention is made in the paper. 



With reference to the Laurentian, he maintained its claim to be 



regarded as a regularly stratified system probably divisible into two 



or three series, and characterized in its middle or upper portion by 



the accumulation of organic limestone, carbonaceous beds, and iron- 



* By difference. 



