WHITE] NOTES ON CHARACTERISTIC SPECIES. 885 



inflations of the ventrally convex lamina, which gives the margin a 

 slightl^v sinuate trend. This alternatel}- inflated development of the 

 lamina, suggesting a series of rectangular cushions on either side of 

 the midrib, or the expressions of distant sori through the substance 

 of the fern, is a constant character plainly discernible in all parts of 

 the frond. 



The aspect of the larger pinnules is very much like that represented 

 by Brongniart^ in Pecopteiis margmata. But, while the resemblance 

 of the undulate surface and sinuate margins is close, the species from 

 Pennsylvania difi'ers by its smaller size, greater delicacy, narrower 

 pinnules, longer and narrower terminals, as well as by the absence of 

 the flat border of the Old World type. Quite independent of the infla- 

 tion of the lamina, A. Lacoei is separable from the A. MaiitelU and A. 

 Joncliltlca series by the form of the pinnules, which are hardly nar- 

 rowed at the base, but which taper from the base upward, the apices 

 generally appearing as acute. The nerves, which may fork close to 

 the midrib, are nearly straight and regular in passing at a right angle 

 to the margin, thus diflering from those of the A. SeMi or A. grandi- 

 folia types. The latter, however, are too distinct in other respects 

 to require further comparison. 



Although this species is common at the horizon of Lykens coal No. 

 2 in the Southern Anthracite field, it is generally rare in other 

 regions of the Appalachian province. Yet when present it is usually 

 represented by large numbers of individuals. In the anthracite 

 region the species has been found at the New Lincoln mine, the lower 

 Eureka tunnel, and at the supposed horizon of Lykens coal No. 2 in 

 the gap at Pottsville. 



Alethopteris protaquilina sp. nov. 



The essential features of this species are the small proportions of 

 the pinni\? and the close, very compact, oblong, or linear-lanceolate, 

 obtuse pinnules, in which the limb is of about equal breadth at the 

 base, the terminal being small, rather short, undulate and sub-lobate, 

 . while the curved nervation is often concealed within the thick, strongly 

 inflated lamina. The fern belongs to the straight-pinnuled group 

 represented by A. aquilina, A. ambigua, A. Gibsoni^ and A. j>enn8yl- 

 vanica. It is in most cases easily distinguished from the J.. Lacoei by 

 the tapering, corrugated, more acute, and thicker pinnules of the lat- 

 ter, in which the nervation is more distant. The species is for the 

 most part confined to the roof shales of Lykens coal No. 4, at which 

 horizon it occurs at the Brookside mines and in the Pottsville Gap. 



1 Op. cit., p. 291, pi. Ixxxvii, figs. 2. 2a. 



