PI" 



186 



THE GEOLOGICAL HISTORY OF PLANTS." 



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presents a similar appearance. The S. Eeichenbachii is a 

 type more distinct from those nc \y living and those in 

 the Tertiary. It has indeed stiff, pointed leaves, lying 

 forward, but they are arcuate, and the cones are smaller. 

 Tills tree has been known for a long time, and it serves 

 in the Cretaceous as a guiding star, which we can follow 

 from the TJrgoniaa of the Lower Cretaceous up to the 

 Cenomanian. It is known in France, Belgium, Bohemia, 

 Saxony, Greenland, and Spitzbergen (also in Canada and 

 the United States). It has been placed in another genus 

 — Geinitzia — but we can recognise, by the help of the 

 cones, that it belongs to Sequoia. 



Below this, there is found in Greenland a nearly re- 

 lated species, the S. amhigua, Ilr., of which the leaves 

 are shorter and broader, and the cones round and some- 

 what smaller. 



The connecting link between 8. Smitliiana and Reich- 

 enlachii is formed by S. suhidata, Ilr., and S. rifjida^ 

 Hr., and three species (*S'. gracilis, Ilr., 8. fastigiata and 

 8. Gardneriana, Cair.), with leaves lying closely along the 

 branch, and which come very near to the Tertiary species 

 8. Couttsim. We have therefore in the Cretaceous quite 

 an array of species, which fill up the gap between the 8. 

 sempervirens and gigantea, and show us that the genus 

 Sequoia had already attained a great development in the 

 Cretaceous. This was still greater in the Tertiary, in 

 which it also reached its maximum of geographical dis- 

 tribution. Into the present world the two extremes of 

 the genus have alone continued ; the numerous species 

 forming its main body have fallen out in the Tertiary. 



If we look still further back, we find in the Jura a 

 great number of conifers, and, among them, we meet in 

 the genus Pinus with a typo which is highly developed, 

 and which still survives ; but for Sequoia we have till now 

 looked in vain, so that for the present we can not place 

 the rise of the genus lower than the Urgonian of the Cre- 



