OF LOWER G11EENSA.XD PLANTS. /O 



stomates occur frequently on the under surface and interrupt 

 the sclerenchyma layer ; they appear not to do so in the fossil. 

 The palisade-layer in the fossil consists of larger and fewer 

 elements than in the living form, where the cells are more 

 numerous and smaller. The stone-cells scattered in the meso- 

 phyll of the living leaf appear to be absent in the fossil. The 

 vascular bundle seems more highly organised in living leaves 

 than in the fossil, but against this must be set the fact that oven 

 the ultimate twigs of the living plant have larger leaves than 

 the minute leaves of the fossil. 



The axis of the fossil also agrees with the living form in 

 general structure, as well as in the presence of stone-cells in the 

 phloem. 



The other living species of Sequoia, S. sempervirens, has 

 flattened and expanded leaves, unlike the fossil both in external 

 morphology and internal anatomy ; but I was interested to find 

 that the small leaves which are crowded round the lateral axes 

 just beneath the cones, have a structure almost identical with 

 that of the fossil and the living 8. yiyantea. This might well 

 be held as substantial evidence in favour of the view that the 

 small-leaved foliage is the more primitive, and the expanded 

 leaves the later modification in the genus Sequoia. 



It seems not unlikely that the genus Sequoia may be repre- 

 sented in the Wealden deposits by some of the impressions of 

 foliage-twigs of the kind so difficult to determine precisely, 

 which Seward includes in the form-genus Spltemlepulium 

 (Seward, 1895, pp. 199, 206, etc.). Several such "species," 

 which Heer and others have included in the genus Sequoia, have 

 been wisely placed by Seward in th-e non-committal genus 

 SpJunoltpidium, but it should not be forgotten that it is likely 

 that several of them were really Sequoia. 



Hollick and Jeffrey (1909) describe the internal anatomy of 

 some small leafy twigs which much resemble the foliage gene- 

 rally identified as Sequoia lieiclienbaclti (Geinitz) Heer. They 

 show, from the presence of a large pith with stone-cells etc., that 

 the internal anatomy of these minute twigs is not that of the 

 living Sequoias. Regarding Heer's species they say : " As com- 

 monly recognised its geographical distribution covered the United 

 States, Canada, Greenland, and Europe, while stratigraphically 

 it apparently extended from the Upper Jurassic to the end of the 



