REVIEWS 673 
Ross, Lunenburg County, manganese deposits are described as occurring 
along a fissure in granite. Calcite and manganese oxide was deposited 
in this fissure and later movements broke up this vein and formed a 
frault breccia. Secondary enrichment from surface waters has con- 
centrated the manganese oxide into bodies of workable size and high- 
grade ore. 
3. A few preliminary results are given of investigations of peat 
bogs near St. John and Moncton, New Brunswick. 
Part G. The Platinum Situation in Canada, 1918. By J. J. 
O'NEILL. Pp. 19, map. 
The chief platinum-producing areas in Canada are in Ontario, 
British Columbia, and Yukon. In the nickel-copper ores of Sudbury, 
Ontario, platinum occurs as sperrylite, the platinum arsenide. In 
British Columbia platinum is found both in the solid rocks and the 
gravels. In the solid rocks three distinct types of deposits are recog- 
nized—first, in association with chromite in peridotite-pyroxenite 
rocks; second, in association with chalcopyrite deposits; third, in shear 
zones in typical granite. In the gravels of Yukon platinum is widely 
distributed but not in large enough quantities to be profitably exploited 
for this metal alone. 
Canada appears to have possibilities of becoming one of the great 
producers of platinum. In 1918 only one hundred ounces of platinum 
were recovered, but probably more than 50,000 ounces of the platinum 
metals were contained in ores mined in Canada, but not recovered. 
J. F. W. 
The Silurian Geology and Faunas of Ontario Peninsula, and Mani- 
toulin and Adjacent Islands. By M. Y. WititaMs. Canadian 
Geological Survey, Ottawa, Memoir 111, 1919. Pp. 195, 
appendices III, pls. XXXIV, figs. 6, maps 2. 
In this memoir the author gives his conclusions, based on five 
seasons of detailed field work, on the general Silurian problems of south- 
western Ontario. Detailed sections, descriptions, notes on origin and 
correlation, and complete fossil lists for the various members of the 
Silurian system are given. Nine diagrams are given to illustrate the 
conditions of sedimentation during various stages of the Silurian period. 
Nine new species of brachiopods and one new variety are described. 
The three appendices contain descriptions of a new species of brachiopod 
