Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 330 FOSSILS OF UPPER CRETACEOUS BEDS. [Ch. XVII. With these mollusca are associated many Bryozoa, such as Eschara and Escharina (figs. 316, 317), which are alike marine, and, for the most part, indicative of a deep sea. These and other organic bodies, especially sponges, such as Ventriculites (fig. 318), are dispersed in- differently through the soft chalk and hard flint, and some of the flinty nodules owe their irr
Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 330 FOSSILS OF UPPER CRETACEOUS BEDS. [Ch. XVII. With these mollusca are associated many Bryozoa, such as Eschara and Escharina (figs. 316, 317), which are alike marine, and, for the most part, indicative of a deep sea. These and other organic bodies, especially sponges, such as Ventriculites (fig. 318), are dispersed in- differently through the soft chalk and hard flint, and some of the flinty nodules owe their irregular forms to enclosed sponges such as fig. 319 <x, where the hollows in the exterior are'caused by the branches of a sponge, seen on breaking open the flint (fig. 319 b). The remains of fishes of the Upper Cretaceous formations consist chiefly of teeth of the shark family of genera, in part common to the tertiary, and partly distinct. To the latter belongs the genus Ptycho- dus (fig. 321), which is allied to the living Port Jackson Shark, Ces- tracion Phillipiii, the anterior teeth of which (see fig. 322 a) are sharp and cutting, while the posterior or palatal teeth (6) are flat, and analogous to the fossil (fig. 321). Fig. 322. Pig. 321. Palatal tooth of Ptychodtos decv/rrens. Lower white chalk. Maidstone.
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