406 R. C. WALLACE 
tion. The patches, when seen along the bedding planes, have a 
certain linear development, suggesting branching structures rather 
than concretionary arrangements. Vertical sections are, however, 
more commonly roughly circular. The cross-sections are usually 
not more than 13 in. in diameter, while along the bedding planes 
irregularly extended areas 5-6 in. in length are not uncommon. 
Fic. 3.—Slab of limestone, cut parallel to bedding plane 
What are apparently fucoidal traces have been noted on the 
bedding planes of both the Upper and Lower Mottled limestone. 
This may have suggested the only explanation that has been offered 
as to the origin of the mottling of the stone in this district—that 
given by Panton:" 
It [the limestone at East Selkirk] presents a peculiar mottled-like appear- 
ance, which adds much to its beauty as an ornamental stone. This strange 
mixture of brown and white is difficult to account for. In some cases it appears 
t Trans. 15 Man. Hist. and Scient. Soc., Winnipeg, 1884. 
