224 Canadian Record of Science. 
or for Hozoon, and such misapprehensions are not of infre- 
quent occurrence. As to concretions, it is only necessary 
to say that these, when they show concentric layers, are 
deficient altogether in the primary requirements of lamine 
and interspaces ; and under the microscope their structures 
are either merely fragmental, as in ordinary argillaceous 
and calcareous concretions, or they have radiating crystal- 
line fibres like oolitic grains. Laminated rocks, on the 
other hand, present alternate layers of different mineral 
substances, but are destitute of minute structures, and are 
either parallel to the bedding or to the planes of dykes and ~ 
igneous masses. In the Montreal mountain there are 
beautiful examples of a banded dolerite in alternate layers 
of black pyroxene and white felspar. These occur at the 
junction of the dolerite with the Silurian limestone through 
which it has been erupted. Laminated gneissose beds also 
abound in the Laurentian. Still more remarkable examples 
are afforded by altered rocks having thin calcite bands, 
whether arising from deposition or from, vein-segregation. 
One of these now before me is a specimen from the collection 
of Dr. Newberry, and obtained at Gouverneur, St. Lawrence 
County, New York. It presents thick bands of a peculiar 
granitoid rock containing highly crystalline felspar and 
mica with grains of serpentine; these bands are almost a 
quarter of an inch in thickness, and are separated by inter- 
rupted parallel bands of calcite much thinner than the 
others. The whole resembles a magnified specimen of 
Hozoon, except in the absence of the connecting chamber- 
walls and of the characteristic structures. <A similar rock 
has been obtained by Mr. Vennor on the Gatineau; but it 
is less coarse in texture though equally crystalline, and 
appears to contain hornblende and pyroxene. These are 
both Laurentian, and I consider it not impossible that they 
may have been organic; but they lack the evidence of 
minute structure, and differ in important details from 
Hozoon. Another specimen from the Horseshoe Mountain 
in the Western States (I regret that I have mislaid the 
name of the gentleman to whom I am indebted for this 
