No. 449.] NORTH AMERICAN CONIFERALES. 339 



bordered pits, the broadly oblong orifice equal to the outer 

 limits of the pit and chiefly parallel with the cell axis, 1-2, 

 more rarely 3-4 per tracheid. In somewhat sharp and definite 

 contrast to this, 5. sempervirens has large, oval, narrowly bor- 



dered pits, 2-6 per tracheid, the round or broadly oblong orifice 

 either parallel with or diagonal to the cell axis. In Libocedrus 

 the pits are small, narrowly bordered, oval, with a lenticular, 

 diagonal orifice, 1-4 per tracheid. Or again in Lanx amcncana, 

 the pits are "2-6 per tracheid becoming distinctly smaller 

 toward the summer wood where they are abruptly reduced to 2, 

 and finally i per tracheid." In Cupressns pisifcui the pits are 

 "chiefly 2 in radial series, or in the marguml cells and low ra\s 

 upwards of 6 per tracheid." In Taxodinm disticlnim the pits 

 are round, conspicuously bordered and large, with a very nai- 

 rowly lenticular and diagonal orifice which is often as long as 

 the outer limits of the pit. But in the analytical key it will be 

 observed that this genus is naturally brought into close relations 

 with Sequoia which is also distinguished by large, bordered pits. 

 The ultimate differentiation then rests upon the fact that in the 

 latter, the pits are oval, the border often riarroiv, sometimes 

 obscure, while the olbong or lenticular, usually rather broad 

 orifice is generally parallel with the cell axis. As a final illustra- 

 tion the four pits of Pinus monophylla, or the 1-5 throughout. 



