828 THE AMERICAN NATURALIST. (VoL. XXXIX. 
SYNOPSIS OF SPECIES. 
Pits on the lateral walls of the ray cells (2) angled or oval and merging 
into an open, scalariform structure. ! 
, Resinous wood parenchyma prominent throughout in association with the 
vessels. : 
Rays (tangential) narrow, the cells (1) uniform, narrow and oblong. 
Vessels oval, 1- to 2- or more rarely 3-compounded. 
13. S. sessilifolia. 
Resinous wood parenchyma confined to the outer limits of the grow 
ring. : 
Rays (tangential) numerous, resinous, and chiefly narrow. Cells (1) 
somewhat variable, chiefly oblong and narrow, more rarely oval, 
more or less conspicuously unequal. 
Vessels broad (transverse), oval, 1- to 4- or finally 4- to 5-com- 
nded. i à : : ; 14. S. amygdaloides. 
Rays (tangential) resinous, numerous, broader; cells (1) variable, 
oblong to broadly oval and conspicuously unequal. 
Vessels (transverse) predominant throughout, oval, 2- to 4- or finally 
5-compounded. : oa I : z 15. S. discolor. 
Rays (tangential) broad, more or less 2-seriate ; the cells (1) variable, 
oval to oblong and conspicuously unequal. 
Vessels (transverse) chiefly single throughout, but sparingly 2- to y 
compounded. : ; : i j S. lasiolepis. 
Pits on the lateral walls of the ray cells (2) hexagonal or quadrangular, 
forming coarse sieve-plates, but devoid of scalariform structure. 
Resinous wood parenchyma conspicuous throughout the growth ring. 
Resinous wood parenchyma confined to the vessels and the limiting 
zone. 
Rays (tangential) numerous, resinous, 2-seriate in part; the cells 
(1) variable, narrowly to broadly oval, or round, or even pn 
ish, very unequal. . . 10. S. longifolia. 
Resinous wood parenchyma numerous and often forming definite 
tracts 
Rays (tangential) very numerous, narrow ; cells (1) uniform, oval, and 
chiefly equal NENNEN. Q1 X 4 LS o 
Resinous wood parenchyma confined to the limiting zone. 
Rays (tangential) narrow, I-seriate. 2 
Ray cells (1) variable, oblong, narrow or more often broadly oval or 
squarish, unequal. 
Vessels (transverse) 
) and n 
Ray cells (1) uniform in the sa 
rays, 
at first broadly oval; 1- to 3- or finally — 
arrow. : efie, . ^ € 
mé ray but variable between different 
narrowly oblong to oblong, chiefly equal. 
