No. 448.] NORTH AMERICAN CONIFERALES. 



Ginkgo, being the unique representative of an ancient line, 

 cannot very well be brought into the present discussion \cr\ 

 much in detail. On other grounds it is known to be a priniitix e 

 form representing a group distinctly inferior to the Coniterale^. 

 and this view is supported by the disposition of the pits in two 

 series, a character which, if taken alone, would gi\e the genus 

 rank with Torreya taxifolia among the Ta.xaceai, but when 

 regarded collectively, would place the genus distinctly below the 

 Coniferales as a whole. This evidence, then, indicates that the 

 Ginkgoales must have arisen as a side line at some point inferior 

 to the Coniferales, but superior to the Cordaitales. 



In the Taxaceae the bordered pits do not in themselves 

 afford very conclusive evidence as to the relative position of the 

 family. Among the eight investigated species, representative of 

 three genera, only three, and chiefly two variants occur. Taken 

 alone, the disposition of the pits would lead to no final conclu- 

 sion, but other factors permit of placing this family in the 

 inferior position usually assigned to it. Within the genus three 

 variants are found — the 1-2 rows of T. taxifolia, the one row 

 or pairs of T. calif ornica and the strictly i -seriate form ot 

 T. micifem. In Taxus only two variants appear — the one row 

 or pairs of T. floridana and the i-seriate disposition as found in 

 the remaining three species. The one representati\ e of Podocar- 

 pus shows but one variant, and that is i-seriate. h'roni tiiis 

 it is obvious that the generic sequence must be in the ordei 

 given, and that the sequence of species must be approximately 

 as given in the table of anatomical data to follow.' 



The remaining genera of the Coniferales present so few (le\ 1- 

 ations from a typical form, that they cannot be clifterentiated 

 fully on the basis of the bordered j^its. This character never 

 theless has a definite value in association with others, as in tlie 

 genus Sequoia or some of the hard pines, Larix auu ruajia, etc 

 The general sequence of genera may be recognized 1)} the bor- 

 dered pits only in so far as these structure.- >erve to confirm 

 and emphasize the conclusions reached in other ways, and this 

 will become apparent from an insi)ection ot the table ot anatom- 



