228 



THE GEOLOGICAL HISTORY OF PLANTS. 



specimens of Leda limatula, mixed with remains of land- 

 plants. 



The following are the species of plants recognised in 

 these nodules : 



1. Drosera rotundifolia, Linn. In a calcareous nodule 

 from Green's Creek, the leaf only preserved. This plant 

 is common in bogs in Canada, Nova Scotia, and New- 

 foundland, and thence, according to Hooker, to the Arctic 

 circle. It is also European. 



2. Acer spicatum, Lamx. (Acer montanum, Aiton.) 

 Leaf in a nodule from Green's Creek. Found in Nova 

 Scotia and Canada, also at Lake Winnipeg, according to 

 Kichardson. 



3. Potentilla Canadensis, Linn. In nodules from 

 Green's Creek ; leaves only preserved. I have had some 



difficulty in determining these, 

 but believe they must be referred 

 to the species above named, or 

 to P. simplex, Michx., supposed 

 by Hooker and Gray to be a va- 

 riety. It occurs in Canada and 

 New England, but I have no in- 

 formation as to its range north- 

 ward. 



4. Gaylussaccia resinosa, Tor- 

 rey and Gray. Leaf in nodule 

 at Green's Creek. Abundant in 

 New England and in Canada, 

 also on Lake Huron and the Saskatchewan, according to 

 Kichardson (Fig. 77). 



5. Populus balsamifera, 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 Eng- 

 land and Canada. It extends to the Arctic circle, and is 



FIG. 77. Gaylussaccia resi- 

 nosa. Pleistocene, Can- 

 ada. 



