No. 8.] HEER — GIANT TREES OF CALIFORNIA. 469 



we can follow from the Urgon of the Lower Cretaceous up to 

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

 Saxony, Greenland and Spitzbergen. It has been placed in an- 

 other genus — Geinitzia — but I can recognize, by the help of the 

 cones, that it belongs to Sequoia. 



Below this, there is found in Greenland a nearly related species, 

 the S. amblgua, Hr., of which the leaves are shorter and broader, 

 and the cones round and somewhat smaller. 



The connecting link between S. Smithiana and ReicJienbacJiii 

 is formed by S. suhiihxta Hr., and S. rigida, Hr., and three 

 species (/S'. gracilis, Hr., S.fastigiata and >S'. Gardneriana,, Carr.) 

 with leaves lying closely along the branch, and which come very 

 near to the Tertiary species >S'. Couttsice. We have therefore in 

 the Cretaceous quite an array of species, which fill up the gap 

 between the S. semj^ervirens 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 distribution. Into 

 the present world the two extremes of the genus have alone con- 

 tinued ; the numerous species forming its main body have fallen 

 out in the Tertiary. 



JURASSIC. 



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 type which is highly developed and which still sur- 

 vives ; but for Sequoia we have till now looked in vain, so that 

 for the present we cannot place the rise of the genus lower than 

 the Urgon of the Cretaceous, however remarkable we may think 

 it that in that period it should have^ developed into so many 

 species ; and it is still more surprising that two species already 

 make their appearance which [approach so near to the living 

 Sequoia sempervirens and S. gigantea.. 



Altogether, we have become acquainted, up to the present 

 time, with 26 species of Sequoia. The 14 species of the Arctic 

 zone I have described and figured in my " Fossil Flora of the 

 Arctic Regions." 



