No. 467.] STUDY OF THE SALICACEE. 829 
Vessels (transverse) strongly predominant throughout, 2- to 3- or 
more rarely 4-compounded. ; ; i 8.45. alba. 
Ray cells (1) somewhat variable, chiefly oblong or sometimes , 
broadly oval; chiefly equal. 
Vessels (transverse) strongly predominant, 2- to 5-compounded. 
S. lasiandra. 
Ray cells (1) chiefly uniform and oblong, sometimes oval; unequal, 
often twice as broad or twice as high. 
Vessels (transverse) large, strongly predominant, 2- to 3- or rarely 
4-compounded. . ; A ‘ ; S. lancifolia. 
Ray cells (1) uniform, oblong, chiefly equal. 
Vessels (transverse) predominant, at first large, chiefly simple but 
2- or very sparingly 3-compounded. 8. S. brachystachys. 
Ray cells (1) narrow, chiefly uniform, oval or more generally oblong, 
equal 
qual. 
Vessels (transverse) uniform in size and number throughout, 
except at the outer limits of the growth ring where they 
abruptly diminish in size; chiefly 1- often 2- to 3-com- 
pounded. . : : i : : 9. S. scouleriana. 
Rays (tangential) broader, more or less 2-seriate. 
Ray cells (1) uniform in the same ray, variable between different 
rays, oval or squarish, broad, unequal. 
Vessels (transverse) predominant, 2- to 3- or more rarely 5-com- 
pounded. : : ; ; : ; 1. S. Zevigata. 
Ray cells (1) uniform, oval, narrow, chiefly equal. 
Vessels (transverse) single or somewhat 2- to 3-compounded. 
2. S. hookeriana. 
Ray cells (1) thin-walled, uniform, oblong, narrowly oval, equal. 
Vessels (transverse) not predominant, I- to 4-compounded, con- 
spicuously fewer toward the outer limits of the growth ring. 
3. S. uva-ursi. 
1. S. levigata Bebb. 
Transverse —Growth rings very broad; the limiting wood parenchyma 
about 3 cells thick, sparingly resinous. Vessels predominant throughout, 
at first rather large, radially oblong and very gradually reduced in size to 
the outer limits of the growth ring where they are about 1 the original 
dimensions ; 2- to 3- more rarely 5-radially compounded. Medullary rays 
numerous, resinous, prominent, 1 cell wide, distant upwards of 6 rows of 
celis. 
Radial Rays resinous. Cells (1), the upper and lower walls thin and 
not pitted ; the terminal walls finely pitted. Cells (2) sometimes predomi- 
nant; the upper and lower walls thin and not pitted ; the terminal walls finely 
pitted ; the pits on the lateral walls forming a coarse sieve-plate structure. 
