234 Geological Society : — 



ores on a vast scale. He also mentioned the almost universal pre- 

 valence in the northern hemisphere of the great plications of the 

 crust which terminated this period, and which necessarily separate 

 it from all succeeding deposits. He next detailed its special develop- 

 ment on the coast of the Atlantic, and the similarity of this with 

 that found in Great Britain and elsewhere in the west of Europe. 



The Huronian he defined as a littoral series of deposits skirting 

 the shores of the old Laurentian uplifts, and referred to some rocks 

 which may be regarded as mere oceanic equivalents. Its characters 

 in Newfoundland, Cape Breton, and New Brunswick were referred to, 

 and compared with the Pebidian, &c, in England. The questions 

 as to an Upper Member of the Huronian or an intermediate series, 

 the Basal Cambrian of Matthew in New Brunswick, were discussed. 



The very complete series of Cambrian rocks now recognized on 

 the coast-region of Canada was noticed, in connexion with its equiva- 

 lency in details to the Cambrian of Britain and of Scandinavia, and 

 the peculiar geographical conditions implied in the absence of the 

 Lower Cambrian over a large area of interior America. 



In the Ordovician age a marginal and a submarginal area existed 

 on the east coast of America. The former is represented largely by 

 bedded igneous rocks, the latter by the remarkable series named by 

 Logan the Quebec Group, which was noticed in detail in connexion 

 with its equivalents further west, and also in Europe. 



The Silurian, Devonian, and Carboniferous were then treated of 

 and detailed evidence shown as to their conformity to the types of 

 Western Europe rather than to those of America. 



In conclusion, it was pointed out that though the great systems of 

 formations can be recognized throughout the Northern Hemisphere, 

 their divisions must differ in the maritime and inland regions, and 

 that hard and fast lines should not be drawn at the confines of sys- 

 tems, nor widely different formations of the same age reduced to an 

 arbitrary uniformity of classification not sanctioned by nature. It 

 was also inferred that the evidence pointed to a permanent continu- 

 ance of the Atlantic basin, though with great changes of its boun- 

 daries, and to a remarkable parallelism of the formations deposited 

 on its eastern and western sides. 



4. "On a Hornblende-biotite Rock from Dusky Sound, New 

 Zealand." By Captain E. W. Hutton, E.G.S. 



The rock is of eruptive origin, 'and is associated with Archaean 

 schists and gneisses. It is compact, crystalline, of a dark-green 

 colour, and sp. gr. 3-00-3-07. It is composed of two minerals in 

 nearly equal proportions, one of which, a black mica, has the two 

 optic axes nearly coinciding. The other mineral is of a pale bluish- 

 green colour, and moderately dichroic ; it shows an aggregate polari- 

 zation of rather coarse grains, with here and there distinct crystals of 

 considerable size. Often one side of a crystal shows a single twin, 

 while the other side is polysynthetic. The optical characters are 

 those of the monoclinic system, and further investigation proves 

 these crystals to be hornblende. The mineral which shows aggregate 

 polarization is either crushed hornblende or some altered form of it. 



