230 ANATOMY OF THE GYMNOSPERMS 



Tracheids more or less conspicuously rounded throughout. 



Ray cells (radial) somewhat contracted at the ends, strongly 

 resinous. 



Pits on the lateral walls of the ray cells 1-2, rarely 4, per 

 tracheid. 



6. C. macrocarpa. 

 Tracheids barely if at all rounded. 



Ray cells (radial) contracted at the ends, more or less resinous. 

 Pits on the lateral walls of the ray cells 1-2, rarely 3, per 

 tracheid. 



8. C. Macnabiana. 

 Ray cells (tangential) chiefly transversely oval. 



Tracheids more or less rounded throughout. 



Ray cells (radial) somewhat contracted at the ends, barely resinous. 

 Pits on the lateral walls of the ray cells 1-2, more rarely 4, per 

 tracheid. 



7. C. arizonica. 

 Tracheids squarish, the structure open throughout. 



Ray cells (radial) strongly fusiform, generally resinous. 



Pits on the lateral walls of the ray cells 1-2 per tracheid. 



9. C. Goveniana. 



C. * * CUPRESSOXYLON (Cupressinoxylon) 

 Extinct Species 



Tracheids of the spring wood distinctly rounded. 

 Bordered pits obliterated by decay. 



Medullary rays (tangential) 1-3 seriate, the round, thin-walled 

 cells 47 fj. broad. 



10. C. cheyennense. 

 Bordered pits in i row, distant, round. 



Pits on the lateral walls of the ray cells 1-2, chiefly 2, per 

 tracheid. 



Rays (tangential) numerous, the variable cells chiefly broad, 

 oval, or round, sometimes transversely oval. 



1 1 . C. macrocarpoides. 



Bordered pits large, in i row, or often in pairs, and in larger tracheids 

 becoming more or less 2-rowed. 



Pits on the lateral walls of the ray cells 1-2 per tracheid. 



Medullary rays (tangential) i- seriate, the round cells 19 p 

 broad. 



12. C. comanchense. 



