[PKNHALLow] NOTES ON TERTIARY PLANTS 41 



Sequoia langsdorfii, (Brongn) Heer. 



Figs. 2-4. 



Miocene of John Day Valley, Oregon; Mackenzie River and Horsefly River, 



B.C.; Green River Group, Col. 

 Eocene of Alaska and the Great Valley Group, N.W.T. ; Fort Union Group; 



Porcupine Creek. 

 Cretaceous of Nanaimo and Port McNeil. 



Bib. :— Dawson, Trans. R. Soc. Can., XI., iv., 56, 1895; Penhallow, Trans. R. 

 Soc. Can., VIII., iv., 44, 68, 1902; Dawson, B. N. A. Bound. Comm., 

 App. A, 331, 1875. 



In his description of plants from the Great Valley Group, Sir 

 William Dawson distinguished a wood which he assigned to the genus 

 Cedroxylon, but he observed that it might represent the wood of Thuya 

 interrupta which occurs in the Porcupine Creek Group, noting also 

 that the structure resembled that of Thuya occidentalis.^ It is pro- 

 'bable that these observations applied in part at least, to the wood 

 now under consideration, which cannot be distinguished from that of 

 Sequoia langsdorfii derived from Vancouver and from the Horsefly 

 Eiver, B.C.^ A revision of the original diagnosis of this species, based 

 upon all available material, would be as follows : — 



Transverse. — Growth rings medium, strongly defined. Tracheids of the spring 

 wood squarish, large, 52 x 52 microns, the walls 14 microns thick. 

 Summer wood of three to six tracheids in thickness, the transition 

 from the spring wood rather abrupt. Resin cells rather numerous 

 throughout the growth ring and scattering. Resin canals usually 

 absent, but occasionally appearing in a rudimentary form on the 

 outer face of the summer wood. 



Radial. — Medullary rays devoid of tracheids; the parenchyma cells equal to 

 about four tracheids, somewhat constricted at the ends; the upper 

 and lower walls thin and entire; the terminal walls not pitted, 

 straight or curved; the lateral walls with no recognizable structural 

 details. 



Tangential. — Medullary rays uniseriate or rarely 2-seriate in part, the oval or 

 round cells about 31.5 microns broad. 



Sequoia langsdorfii is a species which has long been known to the 

 Tertiary of both Europe and America, where it is both abundant and 

 of very general distribution. Until recently, however, our knowledge 

 of it has rested entirely upon the remains of foliage and fruit, and 

 from these data alone, it has come to be regarded by palgeobotanists 

 generally, as the prototype of the living Sequoia sempervirens. Thus, 

 as long ago as 1869, Schimper directed attention to the very close 



^ B. N. A. Bound. Comm., App. A, 331. 



^ Trans. R. Soc. Can., VIII., iv., 44, 68, 1902. 



