JEFFRKY. — AUArCARlOXYLOX TYPK. 567 



in the pith and often occupy a somewhat ohiicjue position. Fij^ure/, 

 PhUe 8, shows a i)()rtic)ii of one of these somewhat more lii^lily magni- 

 fied. The contrast between its organization and tliat of the onhnary 

 tissues of the pith can cUvirly he made out. In the memoir on the 

 Conifers of Kreischerville, the writer has called attention to the very 

 frc(pient oecurrence of medullary septa of a sclerotic nature in the 

 pith of branches not only of the Brachyoxylon type, but also of the 

 probal)ly still older type, to which the name Araucariopitys has been 

 apjiiied. It is interesting to consider the organization of the pith 

 in the two Cretaceous Arauearioxyla described above. They have 

 the same tendency to form sclerotic diaphragms. Gothan in a recent 

 memoir on the fossil woods of Spitzbergen ^° has questioned the accu- 

 racy of the writer's reference of the genus Araucariopitys to Araucarian 

 rather than to Abietineous affinities, because he thinks it impossible 

 that an Araucarian conifer should have the pith structure and ray 

 structure, which so far as li\ing representatives of the Coniferales are 

 concerned is more characteristic of the Abietineae than of the Arau- 

 cariineae. It is clear that conclusions as to affinities can only be 

 safely drawn after a full and accurate comparison of Mesozoic and 

 li\ing forms. INIost of the results of structural paleobotany, in the 

 case of Mesozoic conifers at any rate, are vitiated by a neglect of this 

 absolutely necessary precaution. 



The writer has not observed the presence of true sclerotic diaphragms 

 in either the seedling stem or the cone-axes of any living Araucarian 

 species. Isolated stone cells are typical of Araucaria, and sclerotic 

 nests which never become so extensive as to constitute true dia- 

 phragms are foimd in Agathis. 



It appears to be definitely established from tlie data supplied in 

 the present article that persistent leaf traces cannot in the future be 

 regarded as an infallible diagnostic of Araucarian woods. It seems 

 further clear that foliar traces of this type are not a primiti\'e feature 

 of Araucarian woods, since they are not characteristic of the seedling 

 structure of living representatives of the Araucariineae, and are not 

 found, in what we must regard on the basis of a great many concurrent 

 lines of evidence, as the older Araucarian types, namely Brachyoxyla 

 and woods of the organization of Araucariopitys. It is moreover ob- 

 vious that medullary diaphragms are equally characteristic of both 

 the older Araucariineae and of the Abietineae living and fossil. Their 

 presence in older Araucarian types, is consequently one more piece 



50 Op. cit. 



