742 report — 1884. 



9. A preliminary Examination of the Silicious Organic Remains in the 

 Lacustrine Deposits of the Province of Nova Scotia, Canada. By 

 Alexander Howard Mackay, B.A., B.Sc. 



Many of the lakes of Nova Scotia contain large deposits abounding in these 

 remains which consist of the silicious skeletons of upwards of sixty species of 

 diatom acete, and of the silicious spicules of at least seven species of fresh-water 

 sponges. The deposits from different lakes are generally marked by a difference in 

 the species present or in their relative proportion. In lakes which are not agitated 

 by large streams bearing earthy sediments during times of freshets, the deposits 

 generally consist of a light slimy brownish mud, sometimes of a depth beyond 

 twenty feet, into which a pole can be easily driven by the hand. This mud when 

 treated so as to eliminate the carbonaceous vegetable matter, leaves a variable per- 

 centage of exquisitely sculptured diatom cells and various forms of sponge spicules. 

 In some places this percentage is very high and the deposit correspondingly whiter 

 and firmer, in some cases consisting nearly of the pure silicious valves and spicules. 

 The diatoniaceas grow not only in the waters of these lakes but iu the streams 

 flowing into them, so that these deposits are not all developed in situ. The sponges, 

 on the other hand, affect the stiller waters of the lake. They attach themselves to 

 and grow upon portions of submerged wood, stone or even sand, sometimes forming 

 extensive incrustations several inches in tbickness, some species extensively lobed 

 and even branching. The sponge-flesh dying away each winter, innumerable 

 microscopic spicula which formed its skeleton are thus scattered in the waters, so 

 that iu some localities the sponge spicides form a greater proportion of the deposits 

 than the valves of the diatomacese. 



Some of these deposits may prove to be of industrial importance, the material 

 being regarded as capable of use as polishing powder for various purposes, and in 

 the manufacture of dynamite. 



The lakes upon which these preliminary observations have been made include 

 Ainslie, in Cape Breton ; Lochaber, in Antigouish Co. ; Mackay, Black Brook, 

 Garden of Eden, Grant, M'Lean, Calder, Forbes, Ben, and Toney Lakes in Pictou 

 Co. ; Mackintosh, Earltown, and Gulley lakes, in Colchester Co. ; the lakes which 

 supply tbe city of Halifax with water, Grand Lake and Dartmouth Lakes in 

 Halifax Co. ; and Kempt Lake, in King's Co. 



Lists of the species of diatomacefe and spougidre detected in the several 

 deposits were given in tbe paper, which was accompanied by microscopical slides 

 and specimens. The author has not yet concluded his researches. 



10. Tenth Report on the Circulation of Underground Waters in the Per- 

 meable Formations of England and Wales, and the Quantity and 

 Character of the Water supplied to various Towns and Districts from 

 these Formations. — See Reports, p. 96. 



11. Fifth and last Report on Fossil Polyzoa. — See Reports, p. 97. 



12. Report on the Exploration of the Raygill Fissure in Lothersdale, York- 

 shire. — See Reports, p. 240. 



WEDNESDAY, SEPTEMBER 3. 



The following Papers and Reports were read : — 



1. The Qeoloaical Age of the Acadian Fauna. By G. F. Matthew, A.M., 



F.R.S.C. 



In this sketch an attempt is made, by comparison with the Cambrian fauna of 

 other countries, and especially of Wales, to fix more exactly than has hitherto been 



