232 THE AMERICAN NATURALIST [Vol. XLVI 



tales. If we follow the Araucariineae backward step by 

 step, as recent additions to our knowledge now permit us 

 to do, into the past, we find that although in the Tertiary 

 they retained very largely the characteristics which they 

 present to-day in the Cretaceous, particularly in the 

 Lower Cretaceous and in the Jurassic, they become less 

 and less like their existing representatives and more and 

 more like the Abietinese, the actually dominant conifers 

 of the northern hemisphere, both in general organiza- 

 tion and wood-structure. To save time let us consider 

 only three points of anatomical organization, for com- 

 parison. The existing Araucariineae are remarkable 

 among conifers and gymnosperms generally, in possess- 

 ing leaf-traces which continue to 'be formed in the wood 

 by the cambium, long after the leaves which they origi- 

 nally supplied have ceased to exist. The old trunk of a 

 Kauri or an Araucaria, for example, shows on the outside 

 of its wood marks representing the traces of leaves, 

 which may have disappeared hundreds of years pre- 

 viously. This feature has been seized upon by Professor 

 Seward as one of undoubted primitiveness. It is cer- 

 tainly bizarre, and if one accepts the unusual as the cri- 

 terion of antiquity, the Araucariineae certainly could 

 qualify for an ancient lineage on this character. This 

 view does not however accord with paleobotanical facts. 

 In the Lower Cretaceous we find very many undoubted 

 Araucarian trunks, in which the leaf-traces were not 

 persistent as in the existing representatives of the tribe 

 and in the Jurassic and Triassic trunks of this type 

 become practically universal. This at once makes it 

 clear that the persistent leaf-trace, so characteristic of 

 the living Kauri and Araucaria, is not an ancestral fea- 

 ture of the Araucarian stock. Eecently we have sent 

 out from Harvard a botanical expedition to Australasia. 

 At my suggestion Messrs. Eames and Sinnott, who were 

 its personnel, have brought back old seedlings of the two 

 existing Araucarian genera. On investigation of the 

 lower region of these in proximity to the cotyledons, it 



