EOZOON CANADENSE. 537 
the cavities, and that of the dividing bands and the projecting 
masses nearly enclosed by the limestone, —is all of the same char- 
acter with that of the surrounding strata’not adjacent to the 
quarry. 
In the direction of the strike of the strata also, at a few yards 
distance from the quarries, the common rock of the region is found 
with apparently no traces of calcareous matter. In the line along 
which most of the quarries occur, there are intervals of several 
miles where no traces of limestone have been found, though the 
ledges are exposed at the surface in numerous places. 
The central and principal part of the mass which filled the veins 
and pockets.and constituted the bulk of the deposit, was a coarsely 
erystalline magnesian limestone, homogeneous in structure and show- 
ing no traces of stratification. In examining numerous specimens 
of this limestone from the different quarries, I have found in it no 
traces of the eozoonal structure. 
The various silicates which form the large number of distinct 
minerals for which these localites are noted, occur only attached to, 
or near, the enclosing walls of the cavities, and generally in bands 
or layers, though sometimes irregularly distributed. They are 
found generally in pretty regular succession. A network of inter- 
lacing crystals of actinolite, with smoky quartz, calcite and phlog- 
opite, may be seen attached to the walls; and passing inward 
_ there are found pyroxene, scapolite, apatite, boltoyjte, fine fibrous 
tremolite, etc.: and also green serpentine in irregular bands or 
layers, traversed by narrow seams of chrysotile; or scattered 
through the rock in irregular rounded grains and masses, with in- 
tervening spaces filled with calcite. 
In these portions of calcite are found the radiating and branch- 
ing forms that have been identified and described as belonging to 
thé structure of Eozoon. The granules of serpentine are some- 
times arranged quite regularly in concentric lines, but more com- 
monly appear irregularly scattered and varying indefinitely in form 
and size. 
Some of the. specimens from Chelmsford show masses of the 
serpentine intersected by narrow seams of chrysotile, and attached 
to portions of the rock in which the decalcified spaces show the 
tubuli in great abundance, attached to the serpentine grains as 
if growing out from their surfaces. Some of the grains are sur- 
rounded by a fibrous layer, closely resembling the “true celj 
