OF THE DIPTEROCARPACEÆ. 75 
different levels. In Shorea obtusa, for instance, they run in the bark 
through the upper halt of the internode, while in S. robusta they do 
not enter the bark until close under the insertion of the petiole. 
This, however, possibly varies in the same species. Pierre states 
(under Pentacme siamensis, plates 225-227) that the cortical leaf- 
traces in Shorea robusta run through two-thirds of an internode. 
I have always found them exceedingly short in this species. 
Burck (Z. c. p. 168) states that in S. scaberrima, aptera of 
section Brachyptera, and in S. Pinanga of section Pinanga, 
the lateral leaf-traces run through the bark for more than 
one internode and a half. For these three species and for 
S. leprosula, Miq. (S. Maranti, Burck), and inappendiculata, 
Burck, of section Mutica, the same author (1. e. p. 171) claims 
four lateral cortical leaf-traces instead of two. Of these four 
traces, which are found in the bark in the upper half of the 
internode, two, according to Burck, enter the petiole at the top 
of it, while the two others, after having run through the bark 
for an internode and a half, enter the petiole at the top of the 
next higher internode. 
In those species which have large stipules there are lateral 
stipular, besides the leaf-traces. These stipular traces either 
branch off from the central cylinder, as is the case in Diptero- 
carpus, or they are branches of the lateral leaf-traces. Burek 
has justly said :—“ Rien n'est plus inconstant, que le nombre 
de canaux dans la tige des Shorea.” At the base of the leaf- 
bearing internodes of S. robusta, for instance, I have found this 
number vary from 3 to 20. 
The petiole below the insertion of the blade as a rule has an 
open semicircle of 7 or 9 halfmoon-shaped vascular bundles, 
either distinct or connected each with a resin-duct. In some 
Species, however (S. obtusa), there is a closed ring of vascular 
bundles. The central mass of vascular bundles consists of one 
or several curved bands, generally without, in some cases with 
1-3 resin-ducts. S. obtusa, however, makes an exception. There 
are in the petiole of this species 10-12 ducts in the outer ring, 
and the same number in the central mass. 
So far as known, all species of Shorea have horseshoe-shaped 
sclerotic cells in the cortex. Some species (5. Talura) have In 
pith and cortex cavities filled with gum, similar to those in 
Doona. . 
This, the largest genus of the order, at present comprises 89 
