I9M) holden— CRETACEOUS LIGNITES 171 



In the next tracheid the pitting becomes uniseriate again, and the 

 bars of Sanio stand out with considerable clearness. Still a third 

 case is presented in fig. 6. At the left are two spiral 



elements 



seems 



next them is a pitted element. Toward the upper end of the latter 

 the pits are biseriate, with faint bars of Sanio; below they become 

 triseriate, and then biseriate again. In the latter case they are 

 alternate, but even here bars of Sanio are present. A similar com- 

 bination of alternating pitting and bars of Sanio is shown in the 

 tracheid at the right of fig. 7 (cone of Araucaria Bidwillii), and 

 similar triseriate pitting in that at the extreme left. 



This type of pitting is uniformly present in this specimen near 

 the pith. Accordingly it 

 the chain of evidence pointing to the derivation of the Araucarineae 

 from the Abietineae. All the araucarian features of wood structure 

 have been previously shown to disappear in the primitive regions 

 of extant araucarians, and now they have all been shown to dis- 

 appear in the stem of extinct ones. 



Brachyoxylon 



Of the remainder of the Cliffwood lignites, a considerable amount 

 belongs to the genus Brachyoxylon. In some cases twigs were found 

 similar in almost every respect to such specimens as Geinitzia 

 Reichenbachi J B r achy phy Hum macrocarpnm, etc., from the Cretace- 

 ous of Kreischerville, New York. 4 Figs. 9 and 10 represent trans- 

 verse and longitudinal sections of one of these. The tracheids have 

 the same combination of araucarian and abietineous pitting, the 

 rays are smooth- walled, there is no wood parenchyma, and, further- 

 more, there are abundant sclerites in the pith. The particular 

 specimen figured here is so like Geinitzia Reichenbachi in the shape 

 and arrangement of stone cells that it seems safe to identify it with 

 that species. 



In other twigs, however, the arrangement of these sderenchy- 

 matous elements is quite different. In figs. 1 1 and 14, for example, 

 they are grouped to form nests, extending like plates, sometimes 

 almost completely across the medulla. As shown in the photo- 



4 Hollick, Arthur, and Jeffrey, E. C, Studies of cretaceous coniferous remains 

 from Kreischerville, X York. Mem. N.Y. Bot. Garden 3:1-38. pis. 1-29. 1909. 



