PREVAILING FAMILIES IN EACH EPOCH. 391 



Tertiary series. Many additional species have been col- 

 lected from each of these series, but are not yet named. 



As the known species of living vegetables are more than 

 fifty thousand, and the study of fossil botony is as yet but in 

 its infancy, it is probable that a large amount of fossil spe- 

 cies lies hid in the bowels of the earth, which the dis- 

 coveries of each passing year will be . continually bringing 

 to light. 



The plants of the First period are in a great measure 

 composed of Ferns, and gigantic Equisetacege ; and of fa- 

 milies, of intermediate character between existing forms of 

 Lycopodiacese and Coniferse, e. g. Lepidodendriae, Sagilla- 

 rise, and Stigmariae; with a few Coniferce. 



Of plants of the Second period, about one-third are 

 Ferns : and the greatest part of the remainder are, Cyca- 

 deas and Coniferse, with a few Liliacese. More species of 

 Cycadeae occur among the fossils of this period, than are 

 found living on the present surface of the earth. They form 

 more than one-third of the total known fossil Flora of the 

 Secondary formations ; whilst of our actual vegetation, 

 Cycadeae are not one-thousandth part. 



The vegetation of the Third period approximated closely 

 to that of the existing surface of the globe. 



Among living famihes of plants. Sea- weeds. Ferns, Lyco- 

 podiacese, Equisetacese, Cycadeae and Coniferae, bear the 

 nearest relation to the earliest forms of vegetation that have 

 existed upon our planet. 



The family which has most universally pervaded every 

 stage of vegetation is that of Coniferae ; increasing in the 

 number and variety of its genera and species, at each suc- 

 cessive change in the climate and condition of the surface 

 of the earth. This family forms about one three-hundreth 

 part of the total number of existing vegetables. 



Another family which has pervaded all the Series of for- 

 mations, though in small proportions, is that of Palms. 



The view we have taken, of the connexions between the 

 extinct and living specimens of the vegetable kingdom, sup- 



