A. Bell — Succession of the Later Tertiaries in Gt. Britain. 75 



Much yet remains to be learnt about the migration of the 

 Mammalia. The Musk Sheep and Glutton in the Forest Bed again 

 reappeared, when a colder period was setting in again, in company 

 with the Northern Lynx and Arctic Fox. But Mr. Howorth has 

 pointed out that rain and damp are the main agents in the delimita- 

 tions of range of the Beindeer and Musk Sheep, the fresh skulls 

 of the latter occurring at lower latitudes than it now occupies. 

 Prof. Boyd Dawkins has so thoroughly entered into this branch of 

 Paleontology, that I prefer leaving such questions to him. 



The Mundesley river bed may probably belong here. The Hydrobia 

 marginata (Belgrandia nana, Sandb.) and Elephas antiquus correlates 

 it to this stage, and if so the presence of the little Chelonian 

 Emys lutaria may place the fluviatile deposit at Wretham Mere, 

 Norfolk, with it. I take it that many of the caves just referred to 

 were inhabited, without cessation, during the following minor 

 glaciation, from Yorkshire southwards. 



1 have lately obtained from the pebble beds overlying the London 

 Clay close to Minster, Sheppey, a flint implement. The two pebble 

 or gravel beds were probably continuous originally. 



The Implement gravels of Heme Bay and the South of Hamp- 

 shire, and the thick yellow clay with large southern erratic rock 

 masses overlying the Selsey mud bed, must be placed here. This 

 clay boulder bed is too often confused with the angular marine 

 gravel above. This gravel I may say helps to form the mass of 

 shingle on the beach, but the shingle is not composed only of this fall 

 or talus, but is augmented by a large accession of rolled pebbles of 

 all ages, travelling from the westward, a fact often lost sight of. 



To this latter half of the Interglacial period I consider the Somme 

 and Seine gravels belong, not to the earlier Thames (Crayford) por- 

 tion. The tuffs of Cannstadt and of Moret in the Seine Valley will 

 probably give the Flora of the time. 



The Minor Glaciation. — Such period will include the Hessle 

 Boulder-clay of Yorkshire, the Upper Boulder-clay of the N. West 

 and Ireland, and probably some of the fossiliferous beds of Scotland, 

 like Paisley and Kilchattan, not possessing so glacial a character as 

 the earlier Fife and Bute beds. 



In Lancashire and Westmoreland alternations are not uncommon, 

 peat containing Mosses, Beetles, etc., not being very rare, the marine 

 fauna in the clays, as in those of the low-lying Caithness lands, 

 mostly being fragmentary and derivative. In the south its influence 

 is chiefly felt in the " trail " Loess, Brick-earth, and Contorted 

 Gravel in the Thames Valley Beds and Tolland's Bay ; and to this age 

 I am disposed to refer the raised beds on the Sheppey and Pegwell 

 Bay Cliffs, and the long stretch of marine detritus and gravels 

 extending from Brighton to Portsmouth, at all heights, from nearly 

 sea-level to upwards of 200 feet. 



The final relics of this era are the Moraines, Eskers, and Karnes, 

 chiefly occurring in Ireland and the North, the Lancashire Shirdley 

 Hill Sands and the Nar Valley. The numei'ous raised marine beds 

 in Devonshire and Cornwall may be referred to here, together with 



