CUPRESSOXYLON 241 



Material silicified. 



Eocene of the Great Valley and Porcupine Creek groups, the province of 



Saskatchewan ; Cretaceous of the south Saskatchewan near Medicine 



Hat, Alberta. 



16. C. Wardi, Knowlton 



" Transverse. Material too fragmentary and too poorly preserved to show 

 the annual rings to the naked eye, but they are apparent under the 

 microscope. The fall wood consists of 3-6 or 3-8 compressed cells 

 in radial rows. The spring wood contains some very large cells, with 

 a diameter in some instances of .062 mm. The number of cells in 

 each row of tracheids varies according to the width of the annual 

 ring, there being frequently as much as 100. Large intercellular 

 spaces occur, especially where additional rows of tracheids have been 

 introduced. 



" Radial. Tracheids provided in i row, or, in some instances, with 2 lon- 

 gitudinal rows of bordered pits. They occupy the center of the cell, 

 and are in close relations, almost touching in some cases. The larger 

 have a diameter of .02 mm., and the smaller a diameter of .015 mm. 

 The medullary rays consist of typical parenchymatous tissue. The 

 individual cells are short, covering a width of 4-8 tracheids. Pits on 

 the lateral walls of the rays not observable, possibly due to the poor 

 state of preservation. The resin ducts (cells) are not very numerous. 

 They are of nearly the same size and shape as the tracheids, and in 

 fact look very much like tracheids with transverse partitions. They 

 are almost always empty. 



" Tangential. The tracheids are not provided with pits on the tangential 

 walls, or at least none have been detected. The medullary rays in 

 many cases are 2 cells broad, and, as indicated, 1-35 cells high. 

 The individual cells of the rays have a diameter of .OI7-.O3 mm." 

 (Knowlton). 



Material silicified. Specimens represented by small fragments only. 

 From the Potomac Formation on the line of the Baltimore and Ohio Rail- 

 road, between Montello and Rives Station, D.C. (Knowlton). 



17. C. columbianum, Knowlton 



" Transverse. The annual ring is very indistinct, although not entirely 

 absent, as slight traces of it are to be observed among a mass of 

 crushed cells. Tracheids in very regular, radial rows, and remarkable 

 for their nearly uniform size and thick walls. The larger cells are 

 about .05 mm. in diameter, the smaller .03 -.04 mm. in diameter. 

 The medullary rays are not abundant and appear very narrow. 



"Radial. The tracheids are thick-walled and covered with I, or rarely 

 2, rows of bordered pits, which are rather small. The larger pits 

 have a diameter of .015 mm. and the smaller a diameter of only 

 .01 mm. The rays consist of long cells, in some cases provided with 

 minute, round punctations. The resin ducts (cells) are numerous. 

 In most cases they consist of a regular chain of short, constricted 

 cells. In some cases they contain small globules of resinous matter. 



