98 
which runs from the small boiling-shed at the road-side 
through the maple bush. For 300 feet (91-5 m.) away 
from the contact is a light-greenish, almost white rock of 
coarsely granular texture, which consists almost wholly of 
diopside, though scapolite, titanite and tremolite are also 
present. A variety composed solely of tremolite is found 
more especially at the edge of the diopside rock, away 
from the igneous intrusion. Between the diopside rock 
and the normal limestone is a zone of serpentine varying 
in width from 10 to 100 feet (3 to 30:5 m.). For the 
most part the serpentine and calcite show the indefinite 
arrangement of ordinary ophicalcites, but at one or two 
points they show that arrangement which has given rise 
to the name Eozoon canadense. It is important in the 
latter case to note that the width of the serpentine bands 
varies greatly, some specimens showing Io bands per inch 
(4 per cm.), while in others the bands are two inches (4:8 
cm.) wide. The normal limestone is found only at the 
southern edge of the exposure and has the usual impure 
character, mica flakes being the most conspicuous mineral 
associated with the coarsely granular carbonates. 
NATURE OF EOZOON CANADENSE. 
Sections of Eozoon have been so often described that 
it will suffice here to draw attention to the structure of 
the serpentine. Very often it possesses a ‘‘mesh-structure,’’ 
less often a “‘knitted,’”’ and rarely a “‘lattice-structure.”’ 
The two former types are derived from diopside and the 
latter from tremolite. The meagre development of 
cleavage in longitudinal sections of diopside is noticeable 
in thin sections of the diopside rock. For this reason, and 
also because basal sections would naturally be in a minority 
in any rock slice “‘mesh-structure’’ is more common than 
‘“‘knitted-structure.’’ Mesh-structure is usually regarded 
as characteristic of serpentine formed from olivine, but in 
the present case no connexion with any mineral of the 
olivine family can be established; on the contrary, the 
serpentine can be found still retaining kernels of diopside. 
Osann concluded that this mineral association was 
the product of thermal metamorphic action on the Gren- 
ville limestone [2]. The cartographical and further micro- 
scopical study made by the present writer support this 
