150 On the Structure of Sigillaria scutellata, etc. 
The leaf-traces pass through the secondary wood at first at an angle of 
about 60° to the vertical, but their course soon becomes almost horizontal, and 
this is maintained until near the inner margin of the wood, when they again 
bend sharply downwards, and eventually unite with the primary wood in one 
of the grooves of the corona. 
The Eusigillariz are compared anatomically with the Subsigillaric, and it 
is found that there are four points in which they differ. In the Eusigillarie, 
the stems are ribbed and the primary xylem always forms a continuous ring. 
The leaf-traces are monoxylic throughout their course. In the periderm, 
the xylem of the trace divides into two distinct strands, and these persist 
through the leaf-base, into the leaf, until near its apex, as the xylem of the 
foliar bundle. If, however, we regard Sigillariopsis Decaisnei, Ren., as a 
member of the Subsigillariz, a conclusion which seems inevitable, then this 
latter characteristic is common to both groups, though in the Subsigillarie it 
is combined with the diploxylic structure. 
The Eusigillarie are next compared with the various types of structure 
exhibited by Lepidodendron and Lepidophloios, with the conclusion that they 
correspond most closely to the Lepidodendroid trunks of Arran and Dalmeny. 
Anatomically they appear to be remote from Sothrodendron, so far as the 
structure of that genus is known. It is found that,in the absence of the 
cortical tissues, it is not possible to distinguish the stele of a Husigillarian 
stem by any definite characters from that of some Lepidodendree. The genus 
Mploxylon is discussed in this connection, and it is shown that it is by no 
means certain that all the decorticated stems, which have been referred 
to it, belong to the Sigillariz. It is more probable that the stems of 
several distinct genera are here grouped together, if only as a temporary 
expedient. 
