226 Reports and Proceedings : 
the Foraminifera known as Polytrema and Carpenteria ; and, 2ndly, 
by radiating and otherwise arranged tubuli in the shell-walls, only 
represented in recent or fossil forms by the ‘vascular system’ of 
the shells of some Foraminifera. Hence, although the organism 
that has given mass to the limestone in question had a wide-spread 
growth, with layer after layer in considerable thickness, forming a 
reef by itself, yet Dr. Dawson finds it to be Foraminiferal in its 
character, and therefore refers it to the Rhizopods, with the name of 
Eozoén Canadense. ‘The structure of this fossil is often lost in the 
altered limestone, especially when dolomitic; but in some cases 
magnesian silicates (augite, serpentine, &c.) have replaced the sar- 
code or jelly-flesh of the Rhizopod, even in the tubuli or ‘ vascular 
system.’ Hence the order and shape of the chambers are more 
or less distinctly traceable, and the tubuli are replaced by threads of 
mineral matter, remaining after the calcite has been removed by 
dilute acid. Dr. Dawson, however, in transparent slices under the 
microscope, made out the structure of Hozodn, before specimens that 
could be dissected by acid had been experimented upon; and the 
latter confirmed the results he had arrived at. 
The silicates replacing the sarcode of the original animal are white 
pyroxene, serpentine, loganite, and pyrallolite or rensselerite. The 
pyroxene and serpentine are often found in contact, filling con- 
tiguous chambers in the fossil, and were evidently formed in con- 
secutive stages of a continuous process. Sometimes the shell- 
skeleton has been replaced by dolomite, and then the finer details of 
structure are lost. . The infilling of the chambers with the silicates 
in Kozo6n is strikingly analogous to the replacement of the sarcode 
of recent and fossil Foraminifera by glauconite. 
In one of the limestones (Grenville), the thin wavy lamine of 
calcite and serpentine are traceable in patches, about a square foot 
in extent, and 6 or 6 inches thick. Beyond these, a granular mix- 
ture of the two substances, sometimes with the peculiar minute 
structure, represents, 1t would appear, ruined masses of Eozoén, 
passing off into calcareous rock; whilst the whole is both based on 
and covered by white pyroxene in irregular masses, some of them 20 
yards long by 4 or 5 yards wide, full of small patches of calcite, also 
showing the structure of Kozodn. The upper surface of each pyroxenic 
band generally bears a layer of serpentine, from 5}, inch to 6 inches 
thick. Sometimes other modifications of these minerals occur, 
together with lenticular quartzites, 1 foot thick and several yards in 
diameter, containing flakes of graphite. ‘The pyroxenic masses 
characterize a thickness of about 200 feet in the marble, which is one 
of the lowest bands in the Grenville zone, 1500 feet thick altogether, 
but subdivided by great bands of gneiss. The authors state that 
the structure of this serpentinous marble suggests that it has been 
built up as a great Foraminiferal reef; the pyroxenic masses repre- 
senting the older portions, successively broken up and worn down, 
and covered by new growths of Kozodn, represented by the calcareo- 
serpentinous portions. Mr. Sterry Hunt observes that this marble 
shows that the formation of magnesian silicates was not incompatible 
