44 A MANUAL 03? THE C0NIFER.ZE. 



represented by Saxe-Gothaea, which is found at a considerable 

 elevation, associated with a dioecious member of the Cypress tribe 

 (Fitzroya). 



The present distribution of the Coniferae over the surface of the globe 

 is believed to have resulted from the gradual geological changes that 

 have been effected since the first appearance of a Coniferous vegeta- 

 tion in the earlier formations ; and the existing genera and species are 

 believed to have been developed in the course of ages from those that 

 have long since become extinct. 



The evidence adduced in support of this belief consists in the fossil 

 remains of the plants found in the different strata or rocks of which 

 the crust of the earth is composed, and which are proved to have 

 been formed slowly by the gradual action of water, or suddenly by 

 mighty convulsions. It is further proved, that the distribution of land 

 and water on the surface of the globe has not always been the same 

 as it is now; many districts, which are now continents, having been 

 at one time seas, and vice versa ; and also that the changes in climate- 

 have been not less remarkable. Similar formations and consequent 

 changes • are still in progress on a vast scale in every region of the 

 globe by the agency of water, as is seen by the deposits of layers of 

 mud continually accumulating at the mouths of the great rivers, as 

 the Nile, the Ganges, Ho-ang-ho, Mississippi, &c, and which are brought 

 down by their waters in a state of suspension or solution, and forming 

 what are called "Deltas.'' 



From the observed uniformity of Nature's laws and workings, it is 

 reasonable to infer therefore, that a cause constantly operating in this 

 way at the present time in the case of these and other rivers, has 

 also been operating in the same way from remote antiquity. In the 

 course of these formations, " multitudes of plants, including even large 

 trees, have become embedded in the soft deposits of mud, and their 

 remains preserved in the rock, which results from the hardening of 

 the mud.* The soft and delicate parts could not be perpetuated in this 

 manner ; and it is found, in fact, that only the harder parts, like the 

 wood-bark and fruits, are preserved. The softer portions have been, 

 more or less, quickly decomposed ; although under specially favourable 

 conditions, there has been some preservation even of these. These 

 delicate parts have in some instances left impressions in the hardening 

 mud, from which the form, and even the species, can be recognised." f 

 Geologists have classified the different strata into systems, with a 

 subdivision into groups, to which they have given appropriate names. 

 They have also assigned to the groups a chronological order of forma- 

 tion, not indeed by referring them to a particular . year, .or number of 



* It is well-known that in the Mississippi and other great American rivers, thousands of 

 trees float annually down the streams. (Sir Charles Lyell, Geology, p. 481). 

 t Thome's Structural arid Physiological Botany, p. 418. 



