224 THE FOREST LANDS OF NORTHERN RUSSIA. 



distinction between them and living races. Of land plants 

 there have been found cycas-like plants, coniferse, palms, 

 willows, elms, and other species, exhibiting the true dico- 

 tyledonous structure. Nuts allied to those of the cocoa 

 and other palms have been found in the London clay, 

 which belongs to this class of strata; and seeds of the 

 fresh-water characeae or stoneworts, known by the name 

 of gyrgonites so named from the Greek Gyros, curved, 

 and gonos, seed, which is descriptive of their form- are 

 found in the same deposit. Lyell has subdivided the 

 tertiary strata into four groups : named respectively the 

 Eocene, found in Paris, London, and Belgium 3'12 per 

 cent, of the fossils found in which are of recent species. 

 The name is composed of the Greek words Eos, the dawn, 

 and kamos, recent, and was given in allusion to recent 

 species beginning to appear ; but it should be noted that 

 the reference is to animals, and only incidentally to plants. 

 The Meiocene, from Melon, less a designation given, I 

 presume, in relation to those which follow. This is found 

 in Vienna, Bordeaux, Turin, &c., and contains amongst its 

 fossils 18 per cent, of recent species. The Pleiocene, more 

 recent, from Pleion, more ; it is found in Italian and crag 

 deposits, and of its fossils 41 per cent, are of recent species. 

 And the Pleistocene, the most recent from Pleiston, most ; 

 this is found in Sicilian deposits, and 95 per cent, of its 

 fossils are recent. The nomenclature proceeds on the 

 assumption that the greater the proportion of fossils found 

 of species which still exist in a living state, the nearer to 

 our times must have been the period of its deposit. 



The apparent uniformity of heat over the surface of 

 the earth in earlier times, from the equator to the pole, 

 may be attributed to the temperature of the cooling mass 

 being so far in excess of any heat communicated by radia- 

 tion from the sun to it that this scarcely disturbed the 

 equality of the temperature anywhere. But subsequently 

 it was otherwise, and in regard to the tertiary period, it 

 is stated in the paper cited : 



' The chronological order we have followed has brought 



