726 rossiL plants in different strata. 



Fossil Plants in Diffeebnt Strata. — The plants in the strati- 

 fied rooks are either of a marine, fluviatile, lacustrine, or terrestrial 

 nature, according to the state of the globe at the period of their depo- 

 sition. The condition of the strata as regards fossils may depend in 

 some measure on the depth at which they were deposited under the 

 waters of the globe. The state of preservation depends much on the 

 nature of the plant in regard to its anatomical structure. Cellular 

 plants, which are easily destroyed, have in a great measure disap- 

 peared, whUe plants which resist well the decomposing action of water 

 and other agents, such as ferns, occur in great abundance. In the 

 Silurian system, the fossils consist chiefly of invertebrate animals. 

 Lignite has been detected by Hugh Miller in the Old Bed Sandstone 

 of the north, and has been referred to some coniferous plants by Nicol. 

 In the Carboniferous system fossil plants occur in vast quantity. 

 With the Palaeozoic series one great epoch in the Rock formations was 

 concluded, and a change took place so as to usher in the Secondary 

 series. In the Triassic system the fossil remains are few and local, 

 while in the Jurassic and Cretaceous systems they are much more 

 numerous. With the Secondary series of strata a general condition 

 of the globe ended, and a new one commenced with the Tertiary strata. 

 In these we meet with fossil remains nearly resembling or identical 

 with the existing races. The names given to the groups indicate 

 this. In the Eocene group {^uig, dawn, and xaiv6;, fresh) we meet 

 with a certain proportion of living shells. In the Miocene {/iiiiiiii, 

 less) the number of living species increases, although still less in 

 number than the extinct ones ; while in the Pliocene (irXeluv, more) 

 the recent shells outnumber the extinct ones. The differences between 

 the organic contents of one system and another are in proportion to 

 the interval of geological time elapsed between them ; and the older 

 the rocks the more are the fossils distinct from the plants of the 

 present day. The systems of organic life have been adjusted to the 

 condition of land and sea. 



The number of fossil plants known to M. Adolphe Brongniart, ui 

 1836, was 527. In 1845, Goeppert and Bronn stated the number 

 to be 1792 ; linger, in 1850, described 2421 ; while Schimper, in 

 1874, enumerates upwards of 5000. When we consider that of the 

 130,000 plants which may be supposed to constitute the present Flora 

 of the globe, a large proportion consists of cellular plants, which 

 would disappear in the process of fossUisation, it would seem that the 

 total number of known fossil species bears a considerable proportion 

 to those now existing. 



It is impossible in a short treatise like this to allude to many 

 of the fossU species of plants. It wiU. be sufScient to indicate some 

 of the more important genera, and to give an account of their struc- 

 tiu:e and conformation. 



