TRANSACTIONS OF SECTION C. 663 



retiring down gradually descending slopes, many temporary extra-Glacial lakes 

 were formed in front of it, and were drained one after another as it retired to still 

 lower country. Before it had withdrawn from the Winnipeg basin, it was joined 

 by an advancing glacier from the east, and in front of the two, Lake Agassiz, one 

 of the largest of the extra-Glacial lakes, was formed. 



In its final stages the general gathering-ground of the Keewatin glacier seems 

 to have moved still farther eastward, or nearer to the coast of Hudson Bay, and 

 to have broken into several separate centres, one of which lay over the country 

 south-east of Yath-kyed Lake, while another was probably located north of the 

 head of Chesterfield Inlet. 



After the retirement of the Keewatin glacier the land in the vicinity of 

 Hudson Bay stood from 600 to 600 feet below its present level, and gradually rose 

 to its present height. 



7. The Geological Horizons of some Nova Scotia Minerals. 

 By E. Gilpin, Jr., LL.D., F.R.S.C. 



The principal geological horizons of Nova Scotia are the typically developed 

 divisions of the Carboniferous, followed by interrupted representations of the 

 succeeding divisions down to measures referred by the Geological Survey to the 

 Laurentian. 



The Carboniferous aifords copper, coal, iron, manganese, bary tes, galena, gypsum, 

 grindstone and building stone. The Devonian and Silurian are noted for beds of 

 magnetite and hematite, principally in the Oriskany and Clinton horizons 

 respectively. 



The Cambro-Silurian (Longmynd) in one section contains extensive deposits of 

 auriferous quartz worked to some extent. 



The Laurentian exposed in Cape Breton has as yet received little attention 

 from a mineralogical point, but is known to contain gold, copper, iron ore, mica, 

 graphite, marble, &c. 



TUESDAY, AUGUST 24. 

 The following Papers and Reports were read : — 



1. On the Possible Identity of Bennettites, Williamsonia, and Zamites gigas. 

 By A. C. Seward, M.A., F.G.S., Cambridge. 



The author brings forward evidence in support of the organic connection 

 tetween Williamsonia and the Cycadean fronds known as Zamites gigas, L. and H., 

 and in favour of the close relationship, if not identity, of Carruthers' genera 

 Bennettites and Williamsonia. 



In the earliest descriptions of the Jurassic inflorescence known as Williamsonia 

 "Williamson and other authors regarded the genus as the fructification of the .plant 

 which bore the leaves known as Zamites gigas. In 1875 Saporta expressed himself 

 strongly against the generally accepted view as to the union of Williamsonia and 

 Zamites. A recent examination of a series of specimens in the Paris Natural 

 History Museum and elsewhere has convinced the author that Williamsonia and 

 Zamites gigas are parts of the same plant. 



Evidence has been previously brought forward of the practical identity of 



Williamsonia and Bennettites. More recently acquired information leads to the 



conclusion that we are now familiar, not only with the nature of the Bennettitian 



type of inflorescence, but also with the character of the fronds which were, in some 



instances, associated with this Jurassic fructification. 



In view of the facts before us, it is advisable that the generic name Williamsonia 

 should be substituted for the provisional and comprehensive term Zamites as the 

 more suitable generic name of Lindley and Button's species Zamites gigas. 



