[Footnote 183: The reader who desires to understand this subject more fully, should study chap. x. of the _Origin of Species_, and chap. xiv. of Sir Charles Lyell's _Principles of Geology_.]
[Footnote 184: On "Stagonolepis Robertsoni and on the Evolution of the Crocodilia," in _Q.J. of Geological Society_, 1875; and abstract in _Nature_, vol. xii. p. 38.]
[Footnote 185: From a paper by Messrs. Scott and Osborne, "On the Origin and Development of the Rhinoceros Group," read before the British Association in 1883.]
[Footnote 186: American Addresses, pp. 73-76.]
[Footnote 187: Lecture on the Introduction and Succession of Vertebrate Life in America, _Nature_, vol. xvi. p. 471.]
[Footnote 188: _Nature_, vol. xxv. p. 84.]
[Footnote 189: See _The Mammalia in their Relation to Primeval Times_, p. 102.]
[Footnote 190: For a brief enumeration and description of these fossils, see the author's _Geographical Distribution of Animals_, vol. i. p. 146.]
[Footnote 191: Sketch of Palaeobotany in Fifth Annual Report of U.S. Geological Survey, 1883-84, pp. 363-452, with diagrams. Sir J. William Dawson, speaking of the value of leaves for the determination of fossil plants, says: "In my own experience I have often found determinations of the leaves of trees confirmed by the discovery of their fruits or of the structure of their stems. Thus, in the rich cretaceous plant-beds of the Dunvegan series, we have beech-nuts associated in the same bed with leaves referred to _Fagus_. In the Laramie beds I determined many years ago nuts of the _Trapa_ or water-chestnut, and subsequently Lesquereux found in beds in the United States leaves which he referred to the same genus. Later, I found in collections made on the Red Deer River of Canada my fruits and Lesquereux's leaves on the same slab. The presence of trees of the genera _Carya_ and _Juglans_ in the same formation was inferred from their leaves, and specimens have since been obtained of silicified wood with the microscopic structure of the modern butternut. Still we are willing to admit that determinations from leaves alone are liable to doubt."--_The Geological History of Plants_, p. 196.]
[Footnote 192: Sir J. William Dawson's _Geological History of Plants_, p. 18.]
[Footnote 193: "On the Origin of the Flora of the European Alps," _Proc. of Roy. Geog. Society_, vol. i. (1879), pp. 564-588.]
[Footnote 194: Systematic Review of our Present Knowledge of Fossil Insects, including Myriapods and Arachnids (_Bull. of U.S. Geol. Survey_, No. 31, Washington, 1886).]
[Footnote 195: For the facts as to the early appearance of the above named groups of reptiles I am indebted to Mr. E. Lydekker of the Geological Department of the Natural History Museum.]
[Footnote 196: According to Professor Marsh this creature was 50 or 60 feet long, and when erect, at least 30 feet in height. It fed upon the foliage of the mountain forests of the Cretaceous epoch, the remains of which are preserved with it.]
[Footnote 197: For fuller details, see the author's _Geographical Distribution of Animals_, and Heilprin's _Geographical and Geological Distribution of Animals_.]
