6. _Thuja occidentalism_ 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. It is a northern though not arctic species in its geographical 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. 8. _Potamogeton pusillus._ Quantities of fragments which I refer to this species occur in nodules at Green's Creek. They may possibly belong to a variety of _P. hybridus_ which, together with _P. natans_, now grows in the river Ottawa, where it flows over the beds containing these fossils. 9. _Cariceæ and Gramineæ._ Fragments in nodules from Green's Creek appear to belong to plants of these groups, but I cannot venture to determine their species. 10. _Equisetum scirpoides_, Michx. Fragments in nodules, Green's Creek. This is a widely distributed species, occurring in the Northern States and Canada. 11. _Fontinalis._ In nodules at Green's Creek there occur, somewhat plentifully, branches of a moss apparently of the genus _Fontinalis_. [Illustration: Fig. 79.--Frond of _Fucus_. Pleistocene, Canada.] 12. _Algæ._ With the plants above mentioned, both at Green's Creek and at Montreal, there occur remains of sea-weeds (Fig. 79). They seem to belong to the genera _Fucus_ and _Ulva_, but I cannot determine the species. A thick stem in one of the nodules would seem to indicate a large _Laminaria_. With the above there are found at Green's Creek a number of fragments of leaves, stems, and fruits, which I have not been able to refer to their species, principally on account of their defective state of preservation.