eO ROYAL SOCIETY UF CANADA 



CuPKESsoxYLox DAwsoNi, Penh. 



Eocene of the Great Valley and Porcupine Creek series^ Assiniboia, 

 N.W.T. Cretaceous of the South Saskatchewan, near Medicine Hat, 

 Assiniboia. 



Bib;— Trans. R.S.C., IX., iv., 46; Dawson, B.N. A. Bound. Comm., 1875, App. 

 A., 331; Knowlton, Cat. Cret. and Tert. Floras, 80. 



This spo^cies is represented by eight specimens in all, all of which 

 were derived from essentially the same locality, i.e., the Cretaceous 

 formation of the South Saskatchewan, near Medicine Hat. 



C. dawsoni was first recorded from the Eocene of the Great Valley 

 and Porcupine Creek series last year, but the present material neces- 

 sitates some modifications and amplifications of the original diagnosis, 

 which may now be recast as follows : — 



Transverse. — Growth rings variable, chiefly medium to broad. Tracheids of 

 the spring wood large, thin-walled, conspicuously squarish, and pass- 

 ing gradually into 'the usually thin but rather prominent summer 

 wood, which may occasionally become thicker and without definite 

 internal demarcation. Resin passages wholly wanting. Resin cells 

 numerous and conspicuous throughout the growth ring, often in more 

 or less prominent tangential rows. Medullary rays prominent, 

 resinous, 1 cell wide but rather broad, distant 2-9 rows of tracheids. 



Radial. — Medullary rays devoid of tracheids. Ray cells resinous, contracted 

 at the ends, equal to 5-6 spring tracheids; the upper and lower walls 

 thin and sparingly pitted; the terminal walls straight, or sometimes 

 strongly curved, not pitted or locally thickened; the lateral walls 

 with round or oval pits, 1-2 per tracheid in vertical series, or in mar- 

 ginal cells and low rays, or over very broad tracheids, becorning 4 

 per tracheid. Bordered pits large, in one row, often more or less 

 two-rowed. Resin cells numerous, 35-40a wide, 200// long. 



Tangential. — Medullary rays of one kind only and uniseriate; the cells rarely 

 in pairs, large, thin-walled, oval or oblong, usually broad and often 

 becoming transversely oval in all except the terminal cells. Resin 

 cells as in the radial section. 



iSl early all the specimens included in the material now under con- 

 sideration were indicated in the collection by a provisional label, bearing 

 the name cf Salisburia, but this genus has not been found ta be 

 represented by any of the specimens. 



Cupressoxylon daw^sond has heretofore been known to one locality 

 only, but its occurrence near Medicine Hat in what would seem to be 

 great abundance indicates, in the first instance, a much wider geological 

 range than was shown by the first described specimen from the Lignite 



