Ixiv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



decidedly crystalline unstratified rock, in which the constituents 

 are augite, or hornblende, and a felspar, whilst a few investigators, 

 chiefly, however, for a special region, term it an indigenous rock, as 

 having been altered in situ from a sea-borne sediment. 



At the risk of being tedious, I have dwelt on these variations 

 of opinion touching the explanation of facts upon which we are 

 most of us agreed, because the substances thus referred to have, 

 in consequence of recent investigations, been invested with a 

 special interest, and because it has been shown that they are 

 connected with telluric and even cosmical phenomena on a nobler 

 scale than had been anticipated, even by those geologists who had 

 ascribed to them an active part in the elevation of mountain-chains. 



The grandest feat of geological science within the last few years 

 is the astounding extension of the scale of geological time conse- 

 quent on the discovery of the Eozoon Oanadense ; smd, ]9ace the objec- 

 tions of the few who still doubt the organic character of those 

 remains, one of the most curious facts connected with them is their 

 almost universal preservation, wherever they have been found, in 

 minerals of the augite and serpentine class, associated vsdth carbo- 

 nate of lime. The elaborate arguments of Messrs. King and Rowney 

 (Quart. Journ. Geol. Soc. vol. xxii.) in favour of the mineral origin 

 of " Eozoonal " structure had at one time a strong show of support 

 in the fact that these appearances were always observed in serjpen- 

 tinous limestones (ophicalcite) only, whether in Canada, Connemara, 

 Tyree, Bavaria (Dr. Giimbel), or Bohemia (Dr. von Hochstetter), 

 notwithstanding great discrepancy in the age of some of the depo- 

 sits. But the announcement made by Dr. Carpenter, in the Quart. 

 Journ. Geol. Soc. for August last, of Dr. Dawson's discovery of 

 Eozoon preserved in carbonate of lime pure and simple, would appear 

 to close the discussion. Its occurrence in strata of a metamor- 

 phic character would incline, I believe, most geologists to conclude 

 that these minerals had been formed by metamorphic action ; and 

 the undoubted evidence which we possess, that both chrysotile (a 

 fibrous serpentine) and some varieties of augite or pyroxene have 

 been in some cases crystallized out by the action of thermal waters, 

 would countenance the supposition. But Prof. Sterry Hunt, who 

 has so ably laid before us the results of his investigations on the 

 Canadian minerals, has ventured on a bolder hypothesis. The soft 

 portion, or sarcode, of the organisms has been replaced by one or 

 other of the following sihcates — a white pyroxene, a pale-green ser- 

 pentine, and a dark-green alumino-magnesian mineral, allied to 

 chlorite and pyrosklerite, and referred by him to loganite. The 

 septa between the cells retain probably their original composition 

 of carbonate of lime, which in some specimens is associated with 

 carbonate of magnesia. Dr. Hunt infers, from the circumstances of 

 their occurrence, that these silicates were directly deposited in waters 

 in the midst of which the Eozoon was still growing, or had only 

 recently perished, and that they penetrated, enclosed, and pre- 

 served the calcareous structure precisely as carbonate of lime might 

 have done. Not that these silicates are limited by the extent of the 



