238 ANATOMY OF THE GYMNOSPERMS 



C. ** CUPRESSOXYLON (Cupressinoxylon) 



Extinct Species Only 

 10. * * C. cheyennense, Penh. 



Transverse. Tracheids in regular, radial rows, rather uniform, roundish, 

 about 62x62 /j. broad; the walls 15.5 p. thick. Resin passages and 

 special resin cells wanting. Growth rings apparent, very broad ; in a 

 radial extent of 20 mm., 2 growth rings of an equal thickness of 

 10 mm. are represented. The summer wood conspicuous, about 3-4 

 cells thick, the tracheids about 29 x 38 p. broad, the tangential walls 

 about 15.5 p. thick. 



Radial. Ray cells all of one kind, straight ; the upper and lower walls thin 

 and not pitted ; the terminal walls thin and not pitted, straight or 

 curved ; the lateral walls showing no structure which has been oblit- 

 erated by decay ; the cells 3-5 tracheids long. 



Tangential. Rays numerous, medium, 1-3 seriate ; the cells round, thin- 

 walled, 47 /A broad. 



Material silicified. Specimens represented by small portions of stem. 

 From the Cheyenne Formation (Comanche Cretaceous), east of Stokes Hill, 

 Kiowa and Baker County line, Kansas (Prosser). 



11. ** C. macrocarpoides, Penh. 



Transverse. Growth rings rather broad. Tracheids of the spring wood 

 round but thin-walled through the obvious effects of decay ; rather 

 uniform in regular rows, and passing gradually into the rather thin but 

 conspicuous summer wood. Resin passages wholly wanting. Resin 

 cells not recognizable. Medullary rays prominent, often 2 cells wide, 

 distant 1-6 rows of tracheids. 



Radial. Medullary rays wholly devoid of tracheids. Ray cells more or less 

 conspicuously contracted at the ends, equal to about 6 spring tracheids; 

 the upper and lower walls rather thin and sparingly pitted ; the termi- 

 nal walls chiefly straight, sometimes curved, not pitted or obviously 

 thickened locally; the lateral walls with oval or round pits, 1-2, chiefly 

 2, per tracheid. Bordered pits in i row, chiefly distant, round. Pits 

 on the tangential walls of the summer wood not recognizable. Resin 

 cells present on the outer face of the summer wood (?), 30 p. wide and 

 125 /Along. 



Tangential. Fusiform rays wholly wanting. Ordinary rays numerous, low 

 to high, often more or less 2-seriate, rarely 3-seriate in part ; the cells 

 variable, chiefly broad, oval or round, or sometimes transversely oval. 

 Resin cells rather numerous, usually very long, the resin scattering in 

 small globules. 



Material silicified. 



Cretaceous near Medicine Hat, Alberta ; Tertiary of Kettle River, near 

 Midway, British Columbia. 



