Above the orbitoidal limestone is a white limestone, sometimes soft and argillaceous, but in parts very compact and calcareous. It contains several peculiar corals, and a large Nautilus allied to _N. ziczac_; also in its upper bed a gigantic cetacean, called _Zeuglodon_ by Owen.[14] The colossal bones of this cetacean are so plentiful in the interior of Clarke County, Alabama, as to be characteristic of the formation. The vertebral column of one skeleton found by Dr. Buckley at a spot visited by me, extended to the length of nearly seventy feet, and not far off part of another backbone nearly fifty feet long was dug up. I obtained evidence, during a short excursion, of so many localities of this fossil animal within a distance of ten miles, as to lead me to conclude that they must have belonged to at least forty distinct individuals. Professor Owen first pointed out that this huge animal was not reptilian, since each tooth was furnished with double roots (Fig. 224), implanted in corresponding double sockets; and his opinion of the cetacean nature of the fossil was afterwards confirmed by Dr. Wyman and Dr. R. W. Gibbes. That it was an extinct mammal of the whale tribe has since been placed beyond all doubt by discovery of the entire skull of another fossil species of the same family, having the double occipital condyles only met with in mammals, and the convoluted tympanic bones which are characteristic of cetaceans. Fig. 224: Zeuglodon cetoides, Fig 225: Basilosaurus. [1] Quart. Geol. Journal, vol. xx, p. 97, 1864. [2] Palæont. Soc. Monograph, Rept., pt. ii, p. 61. [3] Heer, Climat et Végétation du Pays Tertiaire, p. 172. [4] Bowerbank, Fossil Fruits and Seeds of London Clay, Plates ix and x. [5] Prestwich, Quart. Geol. Journ., vol. x. [6] Second Visit to the United States, vol. ii, p. 104. [7] Cuvier, Oss. Foss., tome iii, p. 255. [8] Sur des Empreintes de Pas d’Animaux par M. J. Desnoyers. Compte rendu de l’Institut, 1859. [9] D’Archiac, Bulletin, tome x; and Prestwich, Quart. Geol. Journ., 1847, p. 377. [10] Quart. Geol. Journ., vol. xii, p. 204, 1856. [11] Murchison, Quart. Journ. of Geol. Soc., vol. v, and Lyell, vol. vi, 1850. Anniversary Address. [12] See paper by the Author, Quart. Journ. of Geol. Soc., vol. iv, p. 12; and Second Visit to the United States, vol. ii, p. 59. [13] Quart. Journ. of Geol. Soc., vol. vi, p. 32. [14] See Memoir by R. W. Gibbes, Journ. of Acad. Nat. Sci. Philad., vol. i, 1847. CHAPTER XVII. UPPER CRETACEOUS GROUP.