618 PROCEEDINGS OF THE AMERICAN ACADEMY. 



hard pines have two or more rows of resin canals in the first annual 

 ring, — soft but one; third, hard pines (except most of the two needled 

 varieties) have stone cells in the pith, — soft have none; fourth, hard 

 pines have not, soft have, tangential pitting of the summer tracheides. 

 Our lignite, then, is nearer the hard than the soft pines, having more 

 than a single row of canals in the first annual ring, and stone cells, but 

 it has also the tangential pitting of a soft pine. On the other hand, 

 Prepinus stateneiisis has the sclerified pith of a hard pine, with the 

 single leaf trace of a soft. Moreover, it has tangential pitting, and 

 but one row of resin canals. It must be borne in mind, however, 

 that we have to do with a brachyblast, and that the second row of 

 resin ducts may be omitted for lack of space. This condition of 

 affairs would be analogous to that of many living hard pines, where, 

 as Pinus rigida, there may be but one row of canals in the short shoot, 

 and sometimes none at all in the first annual ring of the seedling. 

 The fact that the leaf trace of Prepinus statenensis is mesarch, 

 whereas that of our specimen is endark, need not militate against 

 this suggested relationship. In the first place, we have a record 

 of only the fascicular leaves of Prepinus, and of only the primary 

 leaves of this lignite: — there are no grounds for assuming that they 

 must have been alike in this respect. In the second place, it is entirely 

 possible that the strand, though endark in the wood, might acquire 

 mesarch structure in the cortex, or even in the blade of the leaf. An 

 analogous condition is true in the case of the Cycads. Any connec- 

 tion between our specimen and Prepinus viticetensis (16) is less likely, 

 because even though the latter has two rows of resin canals, it lacks 

 the highly characteristic medullary stone cells. The identification of 

 this lignite with the wood of Prepinus, or with either Leptostrobu^, Heer 

 or the somewhat similar Pinites Solmsi (17) of Seward, — both of 

 which are known only superficially, — must remain very problematical. 

 Its relation to other Pifyoxyla should next be considered. As re- 

 gards other lignites from Cliffwood, it differs from Pinus protosclero- 

 pitys in the absence of ray tracheides; and from Pityoxyloii hoUicki 

 Knowlton (18) in that the latter has 'punctations contiguous,' 'thick- 

 walled ray cells,' and often two series of pits. Thickness is, of course 

 a relative term, and more material of our specimen might show diseri- 

 ate pitting. However, Knowlton states that the structure is 'too 

 obscure for accurate description,' so further comparison is impossible. 

 The lignite in question differs from Pinoxylon dacotense, Knowlton, in 

 that the latter has only vertical canals, and from Pityoxylon statenense 

 in that the latter has no stone cells in the pith. Further, it can- 



