JEFFREY. — ARAUCARIOXYLON TYPE. 557 



Gothan has stated that the absence of hars of Sanio is to he explained 

 by the close approximation of tlie ra(hal pits in the traelieids of the 

 Araucarian tribe. It has been shown however that in the seedling, 

 cone-axis and leaf trace of the living Araucarian conifers the pitting 

 is not crowded as is the case in the mature secondary woofl of the 

 trunk and root. This is particularly true of the base of the seedling 

 stem, where typical Araucarian j)itting appears only after man}' years. 

 In spite of the free spacing of the pits of the tracheids in the regions 

 just described bars of Sanio are absent, except in the part of the second- 

 ary wood of the cone axis, immediately adjoining the primary xylem, as 

 has been indicated in the second article of the present series. It 

 follows api)arently that Gothan's explanation of the absence of the 

 bars of Sanio in .cVraucarian woods is not the valid one. On the 

 criteria of the absence of bars of Sanio and presence of Araucarian 

 radial pitting, the Jurassic woods under discussion are clearly of 

 Araucarian affinities. IMoreover if we admit for the sake of argument 

 that the Jurassic woods in question are Abietineous, what is to become 

 of the very numerous woods of the Cretaceous of the Brachyoxylon 

 type, which have traiunatic resin canals but have not normally at 

 least the strongly pitted rays of the Abietineae? They can scarcely 

 be included on the basis of Gothan's view with the Abietineae on 

 account of their not possessing his sovereign diagnostic, Abietineous 

 ray structure. Professor Seward has agreed that woods of this type 

 are " undoubtedh" Araucarian" and it may be assumed that such is 

 the case until serious argument to the contrary can be adduced. ^^ 



Gothan in his articles cited above, has to assume that practically all 

 the coniferous woods of the high arctics are Abietineous in their affini- 

 ties, thus leaving no woody structures for the mmierous Araucarian 

 conifers, which are known to have flourished in that period. Moreover 

 if we grant his identification of Jurassic woods with strongly pitted 

 rays, traumatic resin canals, Araucarian radial pitting and non existent 

 bars of Sanio, as of Abietineous affinities and indicating a recent deri- 

 vation of the Abietineae from Araucarian ancestors, what shall we say 

 of the characteristic Cretaceous woods of the Brachyoxylon type, 

 which resemble these in every respect except in the absence of the 

 Abietineous type of ray? If we derive the Araucarian conifers from 

 the Abietineae no such difficulty arises, because we would expect 

 on such an hypothesis, to find the Araucariineae progressively less 

 like the Abietineous stock in later geological time. On the basis of 



38 The Araucarieae, Recent and Extinct, Pliil. 'I'rans. Roy. Soc. London, 

 Series B. 198, p. 3S2. 



