Symonds — British Fossil Mammals. 419 



arvernensis) is common to the Eed Crag of England and the Pliocene 

 beds of Italy, but appears to have died out before the deposition of 

 the Forest-bed of Cromer. A species of elephant {E. mericlionalis) 

 ranges from the older Pliocene times on to the days when it roamed 

 in the Forest of Cromer on the old lands of Norfolk, and is a good 

 example of the long range in time in which the large mammalia 

 inhabited the earth. 



Post-Pliocene Beponts. — Wo now pass upwards to the domain of 

 existing species of shells, and to strata where no extinct species are 

 known of marine shells. Sir Charles Lyell divides the Post-tertiary 

 formations into two groups, the Post-pliocene and the Eecent, a neces- 

 sary division, for in the Post-pliocene formations many of the mam- 

 malia belong to extinct species, while the shells are identical with 

 those now living ; but in the Eecent formations the mammalia, as 

 well as the shells, are identical with existing species. The oldest of 

 the Post-tertiary deposits is the celebrated Forest of Cromer bed, the 

 remains of an old buried forest which has been traced for 40 miles, 

 and which has been covered up by a series of strata, containing in 

 some parts fresh- water shells and land plants, and animals which are 

 themselves covered up by marine strata with marine shells, shewing 

 that both the site of the Post-pliocene forest and the river silts were 

 afterwards depressed beneath the sea. The shells, whether fluviatile 

 or marine, are all of living species. The trees consist of the Scotch 

 and spruce firs, yew, sloe, oak, alder, and birch, with the yellow 

 and white water lilies, the buckbean, the hornwort, and other pond 

 weeds. The fresh-water shells are such as now inhabit the rivers 

 and ponds of England, but both the plants and the shells indicate that 

 the climate when that ancient forest grew was temperate, but, perhaps, 

 somewhat colder than at present. What strikes the geologist and 

 naturalist most are the remains of the mammalia that are found in 

 these beds. They contain the remains of three species of elephant, two 

 species of rhinoceros, a hippopotamus, a gigantic extinct beaver, the 

 great Irish elk (the Megaceros), several other kinds of deer, bears, the 

 bison, and several marine mammalia, as the walrus and the narwhal. 

 These great quadrupeds must have lived in abundance on the old 

 forest land when the marine mammalia lived in the sea. But mark 

 what follows. Over the extinct forest, and its extinct quadrupeds, 

 its plants, and its shells, rests the Boulder-clay, the unerring, indu- 

 bitable witness that the Forest of Cromer and its history was Pre- 

 glacial, that is to say, the intense cold or maximum of the Glacial 

 Epoch had not arrived when the animals lived and the trees and 

 plants flourished ; nor had the forest land been submerged beneath 

 a Glacial ocean to receive above them the deposits of melting ice- 

 bergs, and their deep covering of ice-borne till, and rocks. 



The Pre-glacial Brick-earths of the Thames Valley. — It appears that 

 certain strata known as the ''Lower Brick-earths of the Thames 

 Valley " are intermediate in time between the Pre-glacial Forest- 

 bed of Cromer and the Glacial Boulder deposits, the mammalia 

 forming a connecting link between the animals of the Forest-bed 

 and those of Post-glacial times. One of the most notable of all 



