THE NEOZOIC AGES. 247 



The London clay is lower Eocene; but in the beds 

 of the Isle of Wight and neighbouring parts of the 

 South of England, we have the middle and upper mem- 

 bers of the series. They are not, however, so largely 

 developed as in the Paris basin, where, resting on the 

 equivalent of the London clay, we have a thick marine 

 limestone, the Calcaire Grossier, abounding in marine 

 remains, and in some beds composed of shells of 

 foraminifera. The sea in which this limestone was de- 

 posited, a portion no doubt of the great Atlantic area 

 of the period, became shallow, so that beds of sand 

 succeeded those of limestone, and finally it was dried 

 up into lake basins, in which gypsum, magnesian sedi- 

 ments, and siliceous limestone were deposited. These 

 lakes or ponds must at some period have resembled 

 the American " salt-licks," and were no doubt resorted 

 to by animals from all the surrounding country in 

 search of the saline mud and water which they afforded. 

 Hence in some marly beds intervening between the 

 layers of gypsum, numerous footprints occur, exactly 

 like those already noticed in the Trias. Had there 

 been a Nimrod in those days to watch with bow or 

 boomerang by the muddy shore, he would have seen 

 herds of heavy short-legged and three-hoofed monsters 

 (Palseotherium), with large heads and long snouts / 

 probably scantily covered with sleek hair, and closely 

 resembling the Modern Tapirs of South America and 

 India, laboriously wading through the mud, and 

 grunting with indolent delight as they rolled them- 

 selves in the cool saline slime. Others more 1'ght and 



