PRESIDENT’S ADDRESS. 343 
THE LAURENTIAN PERIOD. 
The Laurentian in Canada consists of two formadéions. The 
lower—known as the fundamental gneiss—is of igneous origin, 
and probably represents the more or less altered remains of the 
original crust of the earth. The upper formation consists of lime- 
stones and clastic rocks, evidenty of aqueous origin, which are 
called the Grenville and Hastings series. The argillaceous beds 
interstratified with the limestones have been changed into a rock, 
which is also called gneiss, although different in chemical com- 
position from the fundamental gneiss. The Grenville series is 
supposed by Messrs. Adams and Barlow, of the Geological Survey 
of Canada,* to have been deposited at a time when the funda- 
mental gneiss, which formed the bed of the ocean, was in a semi- 
molten or plastic condition, and the sediments sank down into the 
gneiss, so that in places they were entirely enwrapped by it. It is 
in this Grenville series that the structure called Hozdon canadense 
has been found. 
It was the macroscopic characters of Hozodn—the regular con- 
centric layers of which it is generally composed—which first gave 
rise to the idea that it was of organic origin. But these regular 
layers are sometimes very few in number, the greater part of the 
supposed organism being quite irregular in structure; indeed some 
specimens are without any arrangement at all and have been called 
Archeospherine, under the idea that they belonged to a different 
genus to Hozodn. In its microscopic appearence Hozodn must 
closely resemble some of the Foraminifera or it could not have 
deceived such experienced observers as Dr. Carpenter and Professor 
Rupert Jones. However, Mr. H. J. Carter and Professor Mébius 
never allowed that ZHozodn was organic, and Professor Zittel, 
although at first favouring the view that it was a Foraminifer, 
afterwards changed his opinion. Other specimens from Bavaria, 
Bohemia, Ireland, Scandinavia, and Brazil, which at first were 
supposed to be Hozodn, are now acknowledged to be inorganic, and 
somewhat similar structures, have been found in a calcareous vein- 
stone in eastern Massachusetts and in an altered limestone from 
Vesuvius. 
It is, however, chiefly the position in which Hozodn is found which 
makes it impossible to believe that it is of organic origin. Professor 
Bonney, has pointed out that the original Hozodn occurs on the 
periphery of blocks of a variety of pyroxene called Malacolite, 
surrounded by crystalline limestone, and that it is formed by grains 
of this Malacolite, generally altered into serpentine, scattered 
through the limestone.t On the organic hypothesis these blocks 
* American Journal of Science and Art, March, 1897. 
t+ Geological Magazine, 1895, p. 292. 
