so ROYAL SOCIETY OF CANADA 



Resin-cells (transverse) not prominent, remote and more or less obscure 

 on the outer face of the summer wood. 

 Terminal walls of the ray-cells more or less coarsel}' pitted. 

 Rays (radial) with conspicuous tracheids. 



8. TSUGA. 



Rays (radial) wholly without tracheids. 



(An excejîtion is found in A. halsamea, which usually shows 



a few small tracheids.) 



7. Abies. 



1. Thuya, Tourn. 



Transverse. Summer wood thin, rather dense. Resin -passages wholly 

 wanting. Resin-cells more or less prominent, but often widely scat- 

 tering. Tracheids distinctly squari.sh throughout and thin-walled. 



Radial. Ray tracheids wholly wanting. Ray-cells conspicuously con- 

 tracted at the ends, the terminal walls thin and not pitted or locally 

 thickened, usually much curved. Pits on the tangential walls of 

 the summer tracheids only, and small to medium. Tracheids wholly 

 without spirals. 



Tangential. Fusiform rays wholly wanting. Ordinary rays narrow, 

 medium to low, strictly uni-seriate, the cells chiefly narrowly oblong, 

 more rarely oval, barely, if at all, resinous. 



Species. 



1. T. occidentalis, L. 



2. T. gigantea, L. 



2. CuPRESSUs, Tourn. 



Transverse. Summer wood very thin, often barely distinguishable, the 



structure open throughout. Resin -passages none. Resin-cells pi'o- 



minent, rather numerous in tangential rows, scattering or even 



apparently wanting. 

 Radial. Rays chiefly without tracheids. Terminal walls of the ray-cells 



thin and entire, often locally thickened, very commonly curved. 



Tracheids wholly without spirals. 

 Tangential. Fusiform rays wholly wanting. Cells of the rays chiefly 



broad, oval or even transversely oval, resinous ; the rays more or 



less two-seriate. 



Sl'lX'IK.S. 



Sub-genus CIIAMJECYPARIS, Sub-geiiu.-s CUPRESSUS, 



1. C. Lawsoniana, Murr. 4. C macrocnrpa, Hartw. 



2. C. thyoides. L. .5. C. arizonica, Greene. 



3. C. noot/catensis. Lamb 6. C. giiadalupensis, Wats. 



7. C. Macnahiana, Murr. 



8. C. Goveniana, Gord. 



