882. FLORAL ZONES OF THE POTTSVILLE FORMATION. 



are sessile, often less deepl^v dissected; and the relatively shorter, less 

 diverovnt. and frequently slightly constricted lobules of the former 

 species. In Sphenopteris Royi the lobules are more oblique, more 

 broadly coherent, and acute. Finally Sphenopteris patentissima is in 

 general more characteristic of the Culm or Carboniferous limestone 

 of the Old World or of the lower Potts vi He in the New, while S. 

 furcata^ its probable descendant, is later in its appearance, passing 

 from the upper Pottsville into the Lower Coal Measures. 



^plienojjterls j^tenti'^shna is common in the roof shales of L3'kens 

 coal No. 5, and more especially of Lykens coal No. 4, of which it is 

 largely characteristic, at the Brookside and Lincoln mines, as well as 

 at the mines in the Lower L3'kens division, on Broad ^Mountain. It is 

 also present in the zone of Lykens coal No. 4 at the Pottsville Gap. 



Sphenopteris (Diplothmema) furcata Brongn. 



The examination of the American material belonging to the group 

 represented l)y Sjy/ie/wpfen'}^ furcata shows an interesting series of 

 slight modifications. The earlier forms, characteristic of the upper- 

 most beds of the Pottsville formation, are so closel}'^ related to Sphen- 

 ojyh'vU Royi that the two are sometimes difficult to distinguish. The 

 pinnules of the former are, however, generally more dilated, the lacin- 

 ia3 more divergent, acute, and less coherent. The species appears to 

 have diminished in size in the Lower Coal Measures, where it is per- 

 haps inseparable from the type described by Lesquereux as Sphenop- 

 teins trichomanoides Brongn. Frequently the reduced size and the 

 obliquity of the pinnules and lobes appear to distinctly relate it to Sphe- 

 nopteris dissecta and S. alata. The species is readily separated from 

 Sphenopteris patentissima^ of the Lower Lykens division, by the very 

 distant and deeply palmately lobed lower pinnules of the latter, the 

 lobes being relatively long and hardly contracted near the base. In 

 the Southern Anthracite field, Sphenoptei'is furcata occurs in the 

 upper part of the Sewanee zone at the Pottsville Gap and at the New 



Lincoln mine. 



Sphenopteris Royi Lx. 



'i'hc salient feature of this species, which was described by Les- 

 ({ucn'ux,' from the roof of the Sewanee coal at Rockwood, Tennessee, 

 is the oblicjuity of the rather distant, pinnatisect piniuiles, whose 

 very narrow lobes are fixed on a somewhat more elongated axis than 

 in S. fun-afa. or S. p}ate)itissiiii(i^y\h\\e at the same time they are very 

 obJKpu', tapering from a slightly coherent base to an acuminate ])oint. 

 Superficially, this species seems to be intermediate between S. alata 

 on the one hand and S. furcata on the other hand. It is found with 

 S. pahiiatiloha at the New Lincoln colli«>ry. A small and d()ul)tful 

 fragment comes from the Upper Lykens division in the Pottsville Gap. 



1 Cnal Flora, Vol. Ill, p. 708. pi. civ, fig.s. 7-10. 



