542 PROCEEDINGS OF THE AMERICAN ACADEMY. 



question of the value of Araucarian pitting as an indication of Arau- 

 carian affinities is all the more important because it likewise has been 

 made to involve the relationship of the Araucarian Conifers with the 

 Cordaitales of the Paleozoic, which as regards their pitting strongly 

 resemble the conditions typical of the wood of the living Agathis and 

 Araucaria. Still another important question arises in connection 

 with certain features of organization of the Araucarian tracheid as 

 compared with that found in other Conifers. It has been pointed out 

 by Miss Gerry ^^ that the Araucarian Conifers both living and extinct 

 are without the horizontal cellulose bands, between the radial bordered 

 pits, characteristic of all other Conifers. This feature has an added 

 importance from the fact that a similar feature is likewise character- 

 istic of the wood of the Cordaitean gymnosperms. It is the purpose 

 of the present article to deal with these features of the Coniferous 

 tracheids in regard to their value as indications of tribal relationship 

 and evolutional sequence in the Coniferales. 



It will be convenient to begin with the subject of Araucarian pitting. 

 Figure a, Plate 5, shows the crowded alternating arrangement of the 

 tracheary pores, which is regarded as typically Araucarian. The 

 illustration is taken from the wood of Araucarioxylon, norchoraccnsc, 

 from the Raritan Cretaceous of Kreischerville^ Staten Island, N. Y.^^ 

 Figure h, Plate 5, illustrates the arrangement and propinquity of the 

 radial bordered pits in the first annual ring of the same type of lignite. 

 The absence of approximation and consequent flattening of the 

 bordered pits is very apparent. An examination of a considerable 

 number of true Araucarioxyla from the American Cretaceous has led 

 the writer to the general conclusion that no matter how typical the 

 Araucarian arrangement of the pits may be in the mature wood, that 

 in the first annual ring of the stem one alwaj^s finds a marked tendency 

 to the rounded and well spaced pits which are typical of the wood of 

 the Abietineae and allied Conifers. 



Further in connection with recent investigations on woods of the 

 American and European Mesozoic, numerous instances have been 

 described, presenting to a greater or less degree Araucarian character- 

 istics, but with a marked departure from the Araucarian t^^pe of pitting 

 This is notably the case, for example, with the recently established 

 genus Brachyoylon.^° 



An even more striking illustration is supplied by the genus Para- 



18 0-p. cit. 19 Op. oil. 



20 Hollick and Jeffrey, Cretaceous Coniferous Remains from Kreischerville,, 

 Mem. N. Y., Bot. Garden, No. III. 



