In the autumn of 1841 Lyell crossed the Atlantic, and spent thirteen months in the United States, Canada, and Nova Scotia. He worked hard as an observer and recorder, and his comparisons between the strata in the New and Old World are full of interest. Writing from Philadelphia to his father-in-law, Mr. Horner, he says, “Here I am working away in quarries of greensand and picking up belemnites and other cretaceous fossils;” and then to Dr. Mantell, “After staying two days we went by New York and the Hudson to Albany, where I began my explorings in the silurian strata, and from whence I examined the valley of the Mohawk. The Falls of Niagara were as beautiful as I expected, perhaps scarcely so grand, but in geological interest far beyond my most sanguine hopes. So I shall send a paper on the proofs of their recession to the Geological Society. I will not dwell on them now. After spending some time there, I examined seriatim, all the silurian groups and the old red and coal on the borders of Pennsylvania. Returning to Albany, I went south to Philadelphia, and spent four days in collecting in the different divisions of the greensand, and in New Jersey. The analogy of the genera, and even of the species of the European chalk, is most striking.” One of his duties in the United States, was to give a course of lectures at the Lowell Institute, at which his audiences amounted to two thousand. He also went north, and made some most important investigations with Dr. Dawson, then a comparatively unknown school missionary struggling to learn something about nature, and now one of the most distinguished geologists in the world. They dug out roots called by fossilists stigmariæ, which once supported huge trees called sigillariæ in the days of the coal formation, and they measured foot by foot many hundreds of yards of the cliffs of the now celebrated place called Toggins, in Nova Scotia. There they found rows of trees, one over the other, erect, and indicating that, when the part of the earth now cut into by the sea and exposed as a cliff was formed, there was a series of ages, each having its forest, each of which was overwhelmed, and thus forest after forest accumulated. Amongst the trees were some hollow ones, and they contained little fossils, such as shells and scales. They were objects of interest, but it was not until later on that Lyell and Dawson saw their importance. This subterranean forest exceeds in extent and quantity of timber all that have been found in Europe put together. The new deposit of red sand of the numerous estuaries there afforded them endless instruction. “At this place, Truro, the tide is said to rise seventy-five feet, and we see the bottom of a deep salt-water sea, its rippled sands, shells and holes of _Mya_ and _Tellina_ and their tracks, footmarks of birds and worms, the manner in which the clays crack and are marked with the rain, and sometimes shells included recently in solid models of claystone. I have