46 ROYAL SOCIETY OF CANADA 



lower walls thin and much altered by decay, the lateral walls devoid 

 of recognizable markings. 

 Ta?!f7c»/(«/.— Ordinary rays 1 or sometimes 2-seriate in parts; fusiform rays with 

 large resin canal containing thyloses. 



ClJPEESSOXYLOX DAWSONI, 11. Sp. 



Figs. 9-11. 



Eocene of the Great Valley and Porcupine Creek Groups, N.W.T. 



Bib. :— Dawson, B. N. A. Bound. Comm., 1875, App. A, 331. Knowlton, Cat. 

 Cret. and Tert. Floras, 80. 



It is difficult to identify the wood under consideration with the 

 material examined by Sir William Dawson in 1875, but in all probability 

 it is embraced in what he then designated as Cedroxylon, a portion of 

 which, at least, represents Thuya interrupta.^ It may also be repre- 

 sented by the two species designated as (e) and (b). 



The transverse section shows rather broad growth rings with a 

 spring wood composed of large, squarish and thin-walled tracheids 

 •which recall the structure of Cupressus macrocarpa or C. thyoides, a 

 resemblance greatly strengthened by the gradual passage of the spring 

 wood into a thin summer wood composed of 2-4 rows of radially flat- 

 tened tracheids with somewhat thicker walls. The very prominent 

 and resinous rays suggest a further relation to C. macrocarpa, while 

 on the other hand, the very numerous resin cells direct attention to 

 both C. goveniana and C. nutkaensis — particularly to the former. 



In radial section the resinous rays are found to be devoid of 

 tracheids, the terminal walls of the cells are straight or curved, while 

 the lateral walls are marked with oval or rounded pits, often several 

 to the tracheid. The radial walls of the wood tracheids are marked 

 by bordered pits which usually lie in one row or sometimes two rows, 

 thus establishing a resemblance to C. macrocarpa where the pits are 

 often in pairs, but more particularly to C. lawsoniana in which the 

 pits are in one or sometimes two rows. 



In the tangential aspect the wood is seen to have resinous rays 

 of the uniseriate type, the cells of which are very resinous and trans- 

 versely oval or oblong. Three modern species present similar char- 

 acteristics, viz., C. gaudaloupensis, C. goveniana and C. macrocarpa. 

 Among these the resemblance to the latter is very close. From these 

 facts we may conclude that the wood is a specimen of Cupressus, most 

 nearly related to C. macrocarpa among existing species. As identity 

 cannot be fully established through the material at hand, it seems 



'■ B. N. A. Bound. Comm., 1875, App. A, 331. 



