568 DR. M. T. MASTERS : GENERAL VIEW 
GROUPING OF THE SPECIES. 
The following arrangement of sections and species is drawn up 
with a view of facilitating the identification of particular species, 
and is, to a large extent, arbitrary. The main divisions and 
sections, however, are of a more natural eharacter, inasmuch as 
they include species which are evidently closely allied structurally. 
In the division TENUISQUAMA, including the sections 
Srrosus and Cemsra of authors, the relatively thin cone-scales 
constitute a character easily recognized, very constant, associated 
with other marked characteristics, and linking the geuus, so far 
as the characters presented by the cones are concerned, to the 
other genera of the Abietinez. 
In the section Srrosus the resin-canals are marginal and the 
seeds are distinctly winged. Penhallow (Trans. Roy. Soc. 
Canada, 1896, vol. ti. sect. iv. p.34) points out that in P. Strobus 
and some of its allies there are pits on the tangential walls of the 
summer wood, whilst there are none in the corresponding position 
in the other sections into which he divides the genus. 
The section CemBra comprises 5-leaved Pines, with median 
resin-canals and wingless or nearly wingless seeds. 
The division CRASSISQUAM- includes all those species in 
which the cone-scales are notably thickened towards the’ apex, 
and are of a more distinctly woody character than in the pre- 
ceding division. It is here divided into two groups—one in 
which the bud-scales are deciduous, loosely imbricate, and mem- 
branous * ; the other in which the bud-scales are persistent and 
subcoriaceous. The series in which the bud-scales are thin and 
membranous includes two sections—one, INTEGRIFOLIA, in which 
the leaves are quite entire, and the meristele circular in section ; 
the other, SERRATIFOLIa, in which the leaves are serrulate or 
denticulate, especially towards the tip, and in which the meristele 
is elliptic or transversely oblong in section. Certain species, 
such as flexilis and albicaulis, here placed in the Crassifolie, are 
comprised by Engelmann in sect. Strobus. They are, in fact, 
somewhat intermediate in their characters, but on the whole 
they seem more closely related to the species with which they 
are here associated than to those in the section Strobus. 
* In a manuscript list of Conifers prepared by Sir Joseph Hooker, and 
which I was privileged to inspect, great stress is deservedly laid upon the 
nature of the bud-scales for classificatory purposes. 
<7 
