394 Canadian Record of Science 



ferous limestone or other formations is distinctly poor." 

 Accordingly, it will be of interest to notice briefly the 

 chief physical features of the Island of Montreal where 

 the material for this study has been collected. 



The Island of Montreal contains about two hundred 

 and six square miles and is a rough isosceles triangle in 

 shape. The long side is bounded by the Lake of Two 

 Mountains and the Riviere des Prairies, and the other 

 two sides by Lake St. Louis and the St. Lawrence River, 

 respectively. 



The island itself is a part of a great palaeozoic plain, 

 which extends up the Laurentian plateau on the north, 

 southward into the United States, and from the Notre 

 Dame Mountains in Quebec to Lake Huron on the west. 

 The plain is flat, and the average elevation in the vicinity 

 of Montreal is about a hundred feet above the sea level. 

 The whole area is covered with drift and forms excellent 

 farming lands. On the Island, the continuity of the 

 plain is broken by Mount Royal, an igneous mass rising 

 behind the city and occupying an area of about one and 

 a half miles. This is the most westerly of a line' of old 

 volcanoes and laccolites, known as the Monteregian 

 Hills. About the base of Mount Royal, the strata of the 

 lower Silurian are represented by the Trenton Group, 

 which covers the greater part of the island, — with Calci- 

 ferous limestone at the western extremity, Chazy at 

 Point Claire and at Cartierville, and TJtica Shale along 

 the river front at Verdun and Bout de l'lle. 



The upper part of the Palaeozoic and the whole of the 

 Mesozoic and Tertiary are unrepresented, but the Pleis- 

 tocene has left its record in a drift of Leda clay and 

 Saxicava sand and in a series of terraces between) 

 Mount Royal and the harbor, marking the gradual 

 retreat of the Pleistocene Sea. 



Collection of Alqm. 



Throughout the month of October I collected ma- 

 terial for study and classification from a variety of 



