1915] BURLINGAME—ARAUCARIANS 13 
admitted that a shifting of sporangia from one surface of the 
sporophyll has occurred in some pteridophytes. Again, there is 
no evidence that they have occurred in any lycopod that can by 
any possibility serve as a starting-point for modern conifers. 
I have indicated above what seem to me to be the most funda- 
mental objections to the theory, namely, that the individual 
comparisons which can be made between conifers and lycopods 
must be made with plants of the latter phylum which are admittedly 
very remotely related to one another. No single lycopod is known 
that combines within itself any very considerable number of resem- 
blances to the conifers. In a later paragraph I shall return to the 
attempt to evaluate evidence of this sort. It is an interesting 
fact that practically all the evidence for this theory is derived from 
the comparative morphology of adult plants. The two conspicu- 
ous exceptions are (1) SriLEs’s comparison of the erect axillary 
mature megasporangium of the lycopods with the position of the 
very young ovule of the podocarps, which is also erect and axillary, 
but which may later be inverted and carried out and away from 
the axis by the growth of the base of the sporophyll; and (2) his 
argument that the primitive leaf in the conifers was small, narrow, 
and uninerved, because many conifers have juvenile foliage of this 
sort. 
The cordaitean theory 
The majority of writers have held that conifers are ultimately 
to be derived from the Cordaitales. Scorr (53), OLIVER (45), 
WorsbELL (77, 78), CouLTER and CHAMBERLAIN (16), JEFFREY 
(29, 42), THomson (70, 73), and many others have brought forward 
much convincing evidence in support of this view. Although these 
authors agree in general as to the ultimate origin of all conifers 
from a common stock, there is considerable diversity of opinion 
as to the relationship of the tribes. In the present paper we shall 
consider these divergent views only so far as they pertain to the 
origin and relationship of the araucarians. There is a prevailing 
opinion that this tribe is either the primitive basal group of conifers 
or constitutes an independent line by itself. Opposed to this view 
is that of Jerrrey and his students, who have presented much 
evidence to show that the Abietineae are the oldest and most 
