1915] BURLINGAME—ARAUCARIANS 5 
2. A cordaitean connection does not seem probable-——The chief 
arguments for this view they summarize under three heads: (a) the 
presence of hexagonal contiguous pits on the tracheal walls, 
(b) a comparatively wide transition zone from protoxylem to 
secondary wood, (c) a resemblance in the form of the leaf and in 
the general habit of the vegetative shoots. They are of the opinion 
that the first two resemblances are of little significance because 
of their common occurrence among paleozoic plants. They are 
primitive characters; but do not necessarily indicate a relationship 
to Cordaitales. The external form of the leaves is not specially 
significant, for the internal structure does not indicate a close 
affinity with Cordaitales, and furthermore the more ancient 
araucarian leaves are less like those of Cordaitales than those of 
certain modern species. 
Having refuted the supposed arguments for the cordaitean 
connection, they offer certain other objections for good measure. 
They point out that the leaf trace of Cordaitales is double when it 
leaves the primary wood, while that of the Araucarineae is single. 
They cite several other investigators in support of their opinion 
that the ovulate cone is simple in structure. They recognize that 
a comparison can be made between the simple appearing cone 
scales of Araucaria and the apparently double structures of the 
Abietineae. The evidences for the duplicity of Araucaria must 
be derived second hand from the latter. The evidence for their 
double nature rests on the assumption that certain abnormalities, 
in which an ovulate scale is replaced by a foliar shoot, indicate that 
the cone has been derived by condensation of a branching leafy 
shoot whose leaves bore ovules abaxially. While this may be prob- 
able enough (they do not even commit themselves to so much) for 
this group, it is not considered valid evidence in the interpretation 
of the apparently simple cone of Araucaria, which they believe to be 
an older type and more likely to exhibit primitive structures than 
the Abietineae. Their contention is that in the Araucarineae there 
is nothing to explain. The cone is just what it appears to be. 
The inverted vascular supply of the ovule is a normal feature of 
such bundles, and the duplicity is no more than a sort of ligular 
excrescence, such as is common among the Lycopodiales. 
