370 PROCEEDINGS OF THE ACADEMY OF [July, 



iacum Goppert, which is a Jurassic form, but there is no reason to 

 suppose them to be really identical. 



Genua BRACHYOXYLON Hollick and Jeffrey. 

 Brachyoxylon pennsylvanianum sp. nov. Plate IV, figs. 1-5. 



Cedroxylon .' pennsylvanianum, the writer's communication to the Academy, 

 May 18, L909. Peuce huttoniana Witham ? Rogers, W. B.: [Exhibition 

 of Specimens, with Remarks.] Proc. Boston Soc. Nat. Hist., V, pp. 17, 18, 

 1854. 



Transverse Section: Annual ring distinct; tracheids about 

 0.035 mm. in diameter, medium walled. 



Radial Section: Tracheids long, medium walled; bordered 

 pits, 0.010 to 0.012 mm. in diameter, in one or rarely two series, 

 circular, not quite touching, when double in part distant and sub- 

 opposite, yet in other places in the same sections alternating and 

 hexagonal; medullary rays long, without pits; resin ducts absent. 



Tangential Section: Rays simple, containing from 2 to 30 

 cells, usually 7-9, about 0.02 mm. wide; no bordered pits visible. 



Occurrence and Relationships: While the majority of the 

 specimens of silicified wood show the araucarian type of structure, 

 a few fragments, found at four or five localities, differ in having 

 distinctly separated and more or less opposite bordered pits. Ac- 

 cording to Kraus's classification, this material should therefore be 

 referred to the genus Cedroxylon, as was done in the writer's pre- 

 liminary report. But the variation in the character of the pits in 

 different parts of the same section suggests its probable identity 

 with the new genus Brachyoxylon Hollick and Jeffrey, 7 in which both 

 alternating double and non-contiguous single rows of pits are present. 

 The occurrence of this type of structure in so early a geological 

 period as the lower Triassic is interesting, although in the absence 

 of any information as to the leaves or other external characters of 

 the plant, discussion of its relationships or significance would be 

 futile. 



In searching for evidence as to the age of the "Middle Secondary" 

 rocks in Virginia, Rogers had made a microscopical examination of 

 silicified wood from both "western and eastern belts" and thought 

 ii< structure " to agree very nearly with the fossils figured by Witham 

 under the name of Pence Huttonia."* He unfortunately never 



7 .Studies of Cretaceous Coniferous Remains from Kreischerville, N. Y., Mem. 

 N. )'. Hot. Gard., Ill, pp. T.4-57, pi. XIII, 1909. 



8 Witham, II. T. M. The Internal Structure of Fossil Vegetables, p. 70, pi. 



13; reclassified as Cedroxylon huttonianum by Kraus: Schimper's 

 i< PaUontologie Vegetale, II, p. 371, 1870. 



