| [17] | Edin. Phil. Jour., i. 395. |
| [18] | This question was first brought forward by the author in an “Inquiry into the Evidence of the existence of Primitive Races in Scotland prior to the Celtæ.”—British Association Report, 1850. |
| [19] | Hamlet, Act ii. sc. 2. |
| [20] | Montgomery, Pelican Island. |
| [21] | Proceedings of the Academy of Natural Sciences, Philadelphia, July 1859, pp. 178, 186. |
| [22] | Mantell’s Fossils of the British Museum, p. 473. |
| [23] | American Journ. of Science and Arts, vol. xxxvi. p. 199, First Series. |
| [24] | Philosophical Transactions, vol. xxiv. p. 85. |
| [25] | Geol. Survey of Illinois, by A. H. Worthen, vol. i. p. 38. |
| [26] | Types of Mankind, p. 351. |