The importance of all information bearing on the temperature of the Post-pliocene period invests with much interest the study of the land-plants preserved in deposits of this age. Unfortunately, these are few in number, and often not well preserved. In Canada, though fragments of the woody parts of plants occasionally occur in the marine clays and sands, there is only one locality which has afforded any considerable quantity of remains of their more perishable parts. This is the well-known deposit of Leda clay at Green's Creek, on the Ottawa, celebrated for the perfection in which the skeletons of the capelin and other fishes are preserved in the calcareous nodules imbedded in the clay. In similar nodules, contained apparently in a layer somewhat lower than that holding the ichthyolites, remains of land-plants are somewhat abundant, and, from their association with shells of _Leda glacialis_, seem to have been washed down from the land into deep water. The circumstances would seem to have been not dissimilar from those at present existing in the northeast arm of Gaspé Basin, where I have dredged from mud now being deposited in deep water, living 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 Newfoundland, and thence, according to Hooker, to the Arctic circle. It is also European. [Illustration: Fig. 77.--_Gaylussaccia resinosa_. Pleistocene, Canada.] 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 Richardson. 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 variety. It occurs in Canada and New England, but I have no information as to its range northward. 4. _Gaylussaccia resinosa_, Torrey 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 Richardson (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 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 Richardson constitutes much of the drift timber of the Arctic coast (Fig. 78). [Illustration: Fig. 78.--_Populus balsamifera_. Pleistocene, Canada.]