Page:Early Man in Britain and His Place in the Tertiary Period.djvu/47

] According to the observations of Mr. Sorby on the marine currents, the sea in which the Post-nummulitic rocks of the Isle of Wight were deposited was shut off from the Atlantic by a barrier of land running due south from Dorset, Devon, and Cornwall, towards Normandy and Brittany, the main body of the ocean being to the east or south-east, and extending at least as far to the north as Denmark.

This sea teemed with life of various kinds, now to be found, for the most part, in the warmer regions of the ocean. Gigantic sharks, rays, sword-fishes, and sturgeons, and the peculiar armour-clad fish the Lepidosteus, found their prey in vast abundance. There were turtles also innumerable, and sea-snakes, some of which (Palæophis) were twelve feet long. Among the more important mollusca we may notice the nautilus, the cone, volute, cowrie, olive, and large spindle shells (Fusus), which belong to the marine fauna of the tropics.

The Eocene lakes, rivers, and seas were singularly rich in reptilian life. "More true turtles," writes Professor Owen, "have left their remains in the London Clay, at the mouth of the Thames, than are now known to exist in the whole world; one (Chelone gigas) is of enormous size, with a head upwards of a yard across. Emys and Platemys haunted the rivers, while the estuaries were the feeding-places of the soft turtles (Trionyx), and basking on the shores were to be seen crocodiles, alligators, and the long-snouted gavial, now only living in the rivers of India."