370 The American Geologist. June, 1892 
far obtained, Mr. Tyrrell is inclined to regard the horizon as 
probably interglacial, to which it will be referred for the present. 
Mr. Tyrrell further expresses the opinion that the post-glacial de- 
posits of Township 3, near Pilot Mound, may be the interglacial 
deposits of Churchbridge farther north, the glacier in its latest 
advance not having reached to the former place. 
Microscopical examination shows that the two specimens are 
identical. They are, therefore, referred to the same species. 
Comparison with existing species of Larix show that it possesses 
characters approaching both ZL. occidentalis and L. americana, 
while in other respects it is quite distinct from both. It appears 
to be about midway between the two. It has, therefore, seemed 
expedient to distinguish it by a separate specific name, for which, 
as indicating the principal locality, I would propose L, church- 
bridgensis. 
In the following description I have adopted certain standards 
which will also be employed in future descriptions by me. They 
are as follows: 
The size of cells is the whole width from one primary cell wall to 
its opposite. The thickness of a wall is the distance from the 
center of the primary cell wall to the cell cavity, or one-half the 
total thickness. The pits of the medullary ray as exposed in 
radial section, are determined for the area of each wood cell— 
autumn or spring—covered by the medullary ray cell. The 
hight of the large medullary rays in tangential section, is ascer- 
tained by counting from each end towards the center, until the 
first pair of cells is reached. All others are included in the 
central group. The rays are described as unequal when the ex- 
tension on one side of the central group is longer or shorter than 
on the other side. The thickness of the walls in medullary rays, 
is the whole width. The upper, lower and side walls of a medul- 
lary ray are those which would occupy the same relative positions, 
assuming the specimen to be placed vertically and the observer to 
look radially outward or inward. 
Larix churchbridgensis, n. sp. 
Transverse. Growth rings narrow. No very obvious demarca- 
tion between the spring and autumn woods, transition gradual; 
the spring wood at least equal to or twice the autumn wood. 
Wood cells disposed in radial rows. The autumn cells 14.4x24 
