On Specimens of Eozoon Canadense. 215 
manner in which these veins cross the forms of Eozoon in 
truth present an additional proof that these are original en- 
closures in the limestone, and not products of any subse- 
quent change. 
7. In connection with this I would refer to a fact which I 
have often previously mentioned, namely, that the Lauren- 
tian limestones, when destitute of the laminated forms char- 
acteristic of Eozoon, are nevertheless often filled with small 
patches showing the minute structures. These I regard as 
fragments of Eozoon broken up and scattered by the cur- 
rents. In this case, the remainder of these bands of lime- 
stone must be composed of fragments of other organisms 
which not being porous have not been so preserved by in- 
filtration as to be distinguishable. In the original investi- 
gation of Eozoon, however, a great number of slices of these 
fragmental limestones were prepared by Mr. Weston the 
lapidary of the Geological Survey, and carefully examined, 
and though they showed no distinct structure exccpt that of 
EKozoon, I felt convinced, and expressed this conviction in 
my original description, that these fragments presented such 
traces of structure as one is familiar with in metamorphosed 
organic limestones of more modern date.* At Cote St. Pierre 
there are several layers of limestone and dolomite studded 
with this fragmental Kozoon, and in specimens from Brazil, 
from Warren County, New York, and from Chelmsford in 
Massachusetts, and St. John, New Brunswick, the traces of 
Eozoon which I have observed consist of these fragments. 
8, In slicing one of my specimens from Cote St. Pierre, I 
have recently observed a very interesting peculiarity of 
structure, which deserves mention. It is an abnormal thick- 
ening of the calcareous wall in patches extending across the 
thickness of four or five lamelle, the latter becoming slight- 
ly bent in approaching the thickened portion. This thick- 
ened portion is traversed by regularly placed parallel canals 
of large size, filled with dolomite, while the intervening 
calcite presents a very fine dendritic tubulation. The longi- 
tudinal axes of the canals lie nearly in the plane of the ad- 
* Especially the finely granular structure above referred to. 
