THUJOPSIS 2 1 5 



uniform and thin-walled. Bordered pits on the tangential walls of the 

 summer tracheids few and obscure. Medullary rays prominent, I cell 

 wide, distant about 2-10 tracheids. 



Radial. Cells of the medullary rays not much contracted at the ends; 

 the upper and lower walls rather thin, but very unequal and obscurely 

 pitted ; the terminal walls thin, often obscure, not pitted or locally 

 thickened, diagonal and chiefly straight ; the lateral walls with con- 

 spicuously bordered pits, oval, with a diagonal, lenticular-oblong 

 orifice, chiefly 2 per tracheid in radial series, equal to about 4-9 

 tracheids. Bordered pits round, about two thirds the width of the 

 tracheid, in open rows, the orifice round, concentric, in the summer 

 wood becoming lenticular, diagonal. Pits on the tangential walls of 

 the summer tracheids distant, rather obscure. Spirals of the tracheids 

 2-seriate, distant 12.5-25 p., the angle 66.1, vestigial in the summer 

 wood. 



Tangential. Bordered pits on the tangential walls of the summer tra- 

 cheids not very numerous, in distant groups. Rays low to high, 

 numerous. 



3. THUJOPSIS, SIEB. ET Zucc. PLATES 24 AND 25 



Transverse. Growth rings usually very narrow. Resin passages wholly 

 wanting. Resin cells not numerous but prominent, rarely zonate. 



Radial. Ray tracheids wholly wanting. Bordered pits generally rather 

 numerous, in i row. Tracheids wholly without spirals. 



Tangential. Fusiform rays wholly wanting, the i-seriate rays low, resinous. 



1. T. dolabrata, Sieb. et Zucc. 



Jap. = Hiba 



Transverse. Growth rings very narrow and variable. Summer wood 

 rather open, sometimes dense, thin, of 2-10 tracheids, the transition 

 to the spring wood rather gradual. Spring wood very open, the 

 tracheids large, squarish-hexagonal, in very regular rows, uniform, 

 very thin-walled. Resin cells very prominent, not numerous, scatter- 

 ing throughout the growth ring, not obviously zonate. Medullary 

 rays prominent and resinous, not numerous, i cell wide, distant 2-12 

 or sometimes 16 rows of tracheids. 



Radial. Rays somewhat resinous. The cells conspicuously contracted at 

 the ends, equal to 5-6 spring tracheids ; the upper and lower walls 

 thick, sparingly pitted ; the terminal walls thin, often curved, not 

 pitted or locally thickened ; the lateral walls with small, obscurely 

 bordered pits, the large orifice broadly lenticular or oval, about 1-2 

 per tracheid. Bordered pits round or elliptical, nearly as broad as 

 the tracheid, rather numerous, in i row. Pits on the tangential walls 

 of the summer tracheids few, very flat, and rather obscure. Resin cells 

 15-25 //, wide, chiefly 225 p. long. 



Tangential. Rays low, not very broad, resinous ; the cells oval or oblong, 

 rarely round, rather thick-walled, i-seriate. 



