Zeuglodon cetoides, Owen.
Basilosaurus, Harlan.
Fig. 191. Molar tooth, natural size.
Fig. 192. Vertebra, reduced.
The colossal bones of this cetacean are so plentiful in the interior of Clarke County 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 70 feet, and not far off part of another backbone nearly 50 feet long was dug up. I obtained evidence, during a short excursion, of so many localities of this fossil animal within a distance of 10 miles, as to lead me to conclude that they must have belonged to at least forty distinct individuals.
Mr. Owen first pointed out that the huge animal was not reptilian, since each tooth was furnished with double roots (see [fig. 191.]), implanted in corresponding double sockets; and his opinion of the cetacean nature of the fossil was afterwards confirmed by Dr. Wyman and Professor R. W. Gibbes. That it was an extinct species of the whale tribe has since been placed beyond all doubt by the discovery of the entire skull of another fossil of the same family, found to have the double occipital condyles only met with in mammals, and the convoluted tympanic bones which are characteristic of cetaceans.
Near the junction of No. 2. and the incumbent limestone, No. 3., next to be mentioned, are strata characterized by the following shells: Spondylus dumosus (Plagiostoma dumosum, Morton), Pecten Poulsoni, Pecten perplanus, and Ostrea cretacea.
No. 3. ([fig. 190.]) is a white limestone, for the most part made up of the Orbitoides of d'Orbigny before mentioned ([p. 206.]), formerly supposed to be a nummulite, and called N. Mantelli, mixed with a few lunulites and small corals and shells.[208-A] The origin of this cream-coloured soft stone, like that of our white chalk, which it much resembles, is, I believe, due to the decomposition of the orbitoides. The surface of the country where it prevails is sometimes marked by the absence of wood, like our chalk downs, or is covered exclusively by the Juniperus Virginiana, as certain chalk districts in England by yew trees and juniper.
Some of the shells of this limestone are common to the Claiborne beds, but many of them are peculiar.
It will be seen in the section ([fig. 190.] [p. 155.]) that the strata, Nos. 1, 2, 3., are, for the most part, overlaid by a dense formation of sand or clay without fossils. In some points of the bluff or cliff of the Alabama river, at Claiborne, the beds Nos. 1, 2., are exposed nearly from top to bottom, whereas at other points the newer formation, No. 4., occupies the face of nearly the whole cliff. The age of this overlying mass has not yet been determined, as it has hitherto proved destitute of organic remains.
The burr-stone strata of the Southern States contain so many fossils agreeing with those of Claiborne, that it doubtless belongs to the same part of the Eocene group, though I was not fortunate enough to see the relations of the two deposits in a continuous section. Mr. Tuomey considers it as the lower portion of the series. It may, perhaps, be a form of the Claiborne beds in places where lime was wanting, and where silex, derived from the decomposition of felspar, predominated. It consists chiefly of slaty clays, quartzose sands, and loam, of a brick red colour, with layers of chert or burr-stone, used in some places for millstones.