WHITE] NOTES ON CHAEACTERISTIC SPECIES. 



887 



Twin coal in tlie Pottsville Gap. while doubtful fragments, representing 

 a rather more elongated form of pinnule, with rather more distant 

 nerves, come from one of the upper Lykens coals at the New Lincoln 



mine. 



Alethopteris E^vansii Lx. 



PI. CXCII, Figs. 7, 7a, 8, 8a. 



This species, which was described by Lesquereux ^ from the shales 

 accompanying the Sew^anee coal in Tennessee, resemhlos. Zonchojjteris 

 in the form of its pinnae and pinnules, while the nervation suggests 

 one of the more oblique-nerved, straight-pinnuled species of AletJiop- 

 teris, or Call ipter Id turn. The surface of the lamina is rugose and 

 distinctly, though finely, punctate. The nerves are close, regular, 

 rather oblique, forking once or twice. The normal form of this species 

 appears to be generally confined to the region of the Sewell and 

 Sewanee coals of the Southern Appalachian regions and to the approx- 

 imate horizon of Lykens coal No. 3, in the Pottsville Gap. A later 

 form, with very much larger, semi-membranous pinnules, occurs at 

 higher horizons in the Sewanee zone, both in Arkansas and in the 

 Sotithern Anthracite field. Typically, this species occurs 650 feet 

 below the Twin coal in the Pottsville Gap and in the dump from the 

 upper Lykens coals at the Lincoln mine. A variety grandis 

 appears to have come from the roof of Lykens coal No. 1, at the 

 latter localit}". 



Callipteridium pottsvillense sp. nov. 



In this species w^e have one of the composite Pottsville types, pre- 

 senting at once characters of Megalopteris and Alethopteris. The pin- 

 nules are elongate, acute, and thick, resembling very closely those of 

 Megalopteris marginata Lx.^ It is also apparently related to Nerlop- 

 teris lanceolcda of Newberry.' The fern is closely allied to C. tracy- 

 a?ium Lx., from which it differs by the oblong, acute, or acuminate 

 pinnules, w^hich are more unequal at the base, and the less distant and 

 generally oblique nerves. The plant occurs in the Upper Lykens 

 division in the Pottsville Gap. 



Megalopteris plumosa sp. nov. 



The species of the rare genus Mcg(dopt<n-l>i, including the Megalop- 

 teris Daiosoni described from St. John, New Brunswick, appear to be 

 characteristic of the Pottsville formation. Furthermore, the greater 

 number of species thus far described are confined to the Sewanee zone 

 in Arkansas, Tennessee, West Virginia, and Ohio, as well as in 



1 Coal Flora, Vol. Ill, p. 834. 



2Idem, Vol. I, p. 152, pi. xxiv, figs. 4, 4a. 



3 Kept. Geol. Survey Ohio, 1873, Vol. I, Pt. 1 1, pp. 378-381, pi. -xl v, figs. 1,2, 3, 3a. 



