72 THE CANADIAN NATURALIST. [Feb. 



5. Populus bahamifera Linn. Leaves and branches in nodules 

 at Green's Creek. This is by much the most common species, 

 and its leaves are of small size, as if from trees growing in cold 

 and exposed situations. The species is North American and 

 Asiatic, and abounds in New England and Canada. It extends 

 to the Arctic circle, and is abundant on the shores of the Great 

 Slave Lake and on the McKenzie River, and according to Richard- 

 son constitutes much of the drift timber of the Arctic coast. 



Fig. 4. Wood of Populus bal>amifera. 



6. Thuja occidentalis Linn. Trunks and branches in the 

 Leda clay at Montreal. This tree occurs in New England and 

 Canada, and extends northward into the Hudson Bay Territories, 

 but I have not information as to its precise northern range. 

 According to Lyell it occurs associated with the bones of Mastodon 

 in New Jersey. From the great durability of its wood, it is one 

 of the trees most likely to be preserved in aqueous deposits. 



7. Potamogeton perfoliatus Linn. Leaves and seeds in nodules 

 at Green's Creek. Inhabits streams of the Northern States and 

 Canada, and according to Richardson extends to Great Slave 

 Lake. 



