38" The Ottawa Naturalist. [June-July 



containing bryozoa, overlie the Manitoulin dolomite along the 

 south side of Georgian Bay. According to the interpretation of 

 the writer, all the red shales are to be included in the Kagawong 

 member. The age and complete stratigraphic relations of a 

 considerable thickness of gray to green shales, occurring above 

 the red shales at Cabot Head, are not yet definitely determined, 

 although they may, in part at least, represent a later phase of 

 the Kagawong sedimentation. They are overlain by about 6 feet 

 of green shale beneath argillaceous dolomite of Lockport age, 

 as is the case with the Kagawong shale on Manitoulin Island. 



THE SHADE TREES O F OTTAWA. 

 (Continued from page 36). 



ACERACE.5S. 



The Maple familv. It is difficult to decile which is the most 

 valuable among so many useful species. 



The Sugar or Rock Maple, Acer saccharum, probably ranks 

 first because of its well known and valuable qualities. It is 

 among the finest forest trees, and it is handsome and thrives 

 well in the city as long as there is not too much dust and coal 

 smoke. The bark is rugged or shaggy with dee]) long furrows ; the 

 trunk is straight and opens into a shapely oval outline. It is a 

 slow-growing tree, but long-lived. 



The Black Sugar Maple, A. nigrum, grows near the city 

 and may grow along the streets, but it is difficult to distinguish 

 it in winter. 



The White or Silver Maple, .4. saccharinum, is one of the 

 commonest, and is deservedly popular. It is a fast grower. The 

 trunk soon divides into 3 or 4 secondary stems with an upward 

 eep, from which side branches droop outward and downwards. 

 The bark on the branches is smooth and of a light grey color 

 until of considerable size. Both in poise and outline this tree 

 suggests the elm. and the method of city pruning increases the 

 effecr . It is one of the first trees to blossom in the spring. 



The Norwav Maple, .1. platanoides, is an introduced species 

 and deservedly ranks high. The leaves resemble the Sugar 

 Maple, but arc thicker and of a darker green. They remain on 



free a week or more longer than the other maples, and fall 

 without turning color. The petioles exude an acrid milky juice 

 which coagulates. This is characteristic, and is a test easily 

 ide. The bark closely resemble:; the White Ash. On the upper 

 limbs ii is of a brownish-grey color. The trunk is apt to divide 

 too low into numerous small branches, forming abroad, rounded 

 head. At an early stage it should be pruned well up. 



