616 PROCEEDINGS OF THE AMERICAN ACADEMY. 



oflf from the medulla ; Figure e shows one of these leaf traces in cross 

 section. Such leaf traces are cjuite abundant in this specimen, but in 

 the limited amount of material available, there was a complete ab- 

 sence of short shoots, — a remarkable condition for an obvious I*iiy- 

 oxylon. The trace appears to be always single, like those of the 

 fascicular leaves of all living pines, at the point of departure from the 

 pith. Further, like those traces the xylem is entirely centrifugal. 

 Not infrequently a resin canal accompanies the strand in its outward 

 passage, rarely two. 



The rays are of two sorts, — linear and fusiform. The latter are 

 very numerous ; they consist of parenchymatous elements embracing a 

 resin duct, a foliar trace, or both. The character of the linear rays 

 may be inferred from the photomicrographs. The}' are low and highly 

 resinous; the walls are comparatively thin and heavily pitted. The 

 lateral pits are usually one to each cross field, rarely two: they are 

 piciform, with an elliptical opening on the side of the ray and a circu- 

 lar one on that of the tracheide. Unlike living pines, all the cells 

 composing the ray are parenchymatous, although those on the margin 

 are often quite different from the others, being irregular in shape and 

 destitute of resinous content. Figure c shows several instances of 

 this condition. At first sight they appear to be ray tracheides, but 

 the unbordered character of the pits negatives that possibility. 



The tracheides are uniformly small and thick-walled. The pits on 

 the radial wall are uniseriate and scattered; in places, indications of 

 the so called " bars of Sanio" could be distinguished, but as a rule the 

 indifferent state of preservation obscures this feature. In the majority 

 of cases, the pits are confined to the radial walls, but those tracheides 

 laid down at the end of the year's growth, have pores also on the tan- 

 gential wall. As is well known, this is characteristic of all the Abie- 

 tineae except hard pines. 



The characteristics of the pith are evident from Figures b and d. 

 There are two sorts of elements, — thin-walled parenchyma and thick- 

 walled sclerenchyma, the latter standing out as black masses in the 

 photographs. They show a general tendency toward arrangement in 

 horizontal bands, which are not, however, sufficiently localized to 

 form diaphragms. 



It remains now to consider the affinities of this lignite. The pres- 

 ence of resin ducts in both horizontal and vertical planes affiliate it 

 with the genus Pityoxylon, Kraus. Like all previously described 

 Cretaceous Pityoxyla (with the exception of Pinus scituntensiformis 

 and possibly Pinus Nathorsti Conw. (15), about which however it is 



