Stiles . — The Podocarpeae . 501 
has already been expressed by all recent workers on their cone scales, 1 and 
the evidence is against the double nature of the cone scale in these groups. 
Indeed the more primitive Podocarpeae are less like the Abietineae in 
respect of the cone scale than the more modem ones. There is indeed 
a suggestion of doubleness in Dacrydium cupressinmn and Podocarpus, and 
here it has most clearly arisen within the group. 
So we are left with the alternatives of supposing the forms with double 
cone scales as derived from a single-scaled ancestor, or of supposing the two 
lines of descent to be quite distinct. That different groups of Conifers 
have descended from different Pteridophytic or Pteridospermic ancestors 
seems to the writer to be quite impossible. 
There are at present two views as to the phylogeny of the Conifers : the 
more popular one that regards the Conifers and Cordaitales as on the same 
line of descent, and the view that it is in the Lycopodialean alliance that 
we find the nearest approach to the ancestors of the Coniferae of to-day. 
Dr. Scott has made out the best case for the origin of the Araucarian 
alliance from Cordaitales-like ancestors, and the chief points of his argument 
are as follows : 2 
1. The stem structure of the Araucarieae is Cordaitalean. 
2. The roots are like those of Cordaites . 
3. The leaves are parallel-veined. 
4. The staminate strobili and sporangia are like those of Cordaites. 
Now if the Araucarieae and Podocarpeae are such nearly related 
groups as the writer supposes them, in considering the Cordaitalean origin 
of the Coniferae the Podocarpeae must be regarded as of as great importance 
as the Araucarieae. 
Now in the first place the stem structure of the Podocarpeae, although 
of a simple coniferous type, is not at all Cordaitalean, except as regards 
the distribution of the primary vascular bundles, a point of resemblance 
which can be extended to many other forms. As regards the wood there 
is no reason why the Cordaitalean and Podocarpean types of wood should 
not have been derived from the same type ; on the other hand, there is 
no evidence from this character of a connexion between the two orders. 
In the second place the roots of the Podocarpeae, in so far as they 
have been examined, are not particularly reminiscent of the roots of the 
Cordaitales. It is true, indeed, that they are no more reminiscent of 
Lycopod roots ; at least they furnish no definite evidence of a Cordaitalean 
origin. One interesting fact about the roots of the Podocarpeae is the 
possession of tubercles and mycorrhiza which have been compared by 
Osborn with the mycorrhiza in Amyelon, the root of Cordaites . He says 
1 Seward and Ford (’06) ; Stiles (’08), p. 218 ; Thomson (’09 2 ), p. 352 ; Tison (’09), p. 155. 
2 Scott (’09), p. 653. 
