WHITE.] NOTES ON CHARACTERISTIC SPECIES. 899 



frequent dichotomy. The proportions of the variety are very nearly 

 those of the form described 1 )y Star ^ from the Schatzlar series. The 

 plant in hand differs from Spheoiophylliim hifurcatum b}' its more 

 slender stems, by its more delicate, narrower, more rigid, and deeplj^ 

 dissected leaves, and by the linear, obtuse form of the lobes. S. htfur- 

 catwn is more nearl}' connected by its ^•ariable leaf, Avhich is often 

 much less divided, to the S. cuneifoUuin group than is the above- 

 named variety, all of whose leaves are of the more linear, entirely 

 dissected, delicate tj^pe. In the Southern Anthracite field this variety 

 appears to be one of the plants characteristic of the horizon of the roof 

 shales of Lykens coal No. 2, where it is almost invariably associated 

 with Neuropteris Elrodi^ 3fariopteris pygmcea^ and a small species of 

 Eremopteris. It is especially common in this horizon at the Lincoln 

 mines. 



Sphenophyllum bifurcatum Lx. 



This species, as originally described by Lesquereux, from beds now 

 known to lie within the Sewanee zone of the Pottsville formation in 

 Arkansas, appears, as has already been suggested, to be intermediate 

 between SphenoplnjUmn tenerrimimi and S. cuneifolhnn. The less- 

 divided leaves of the Arkansas plant might easily be mistaken in some 

 cases for the latter species. It differs, however, in the position of the 

 leaves and their aspect in the verticils, in the wider form of the leaf, 

 and in the more distant and generally more rigid teeth. The distinc- 

 tions between Sj)Jieno2)hyllu7n hifmxatmnSindi S. tenerrimxiin have already 

 been indicated. The former is not infrequent in the upper part of the 

 Sewanee zone; more rarely it is found in the lower part of the same 

 zone. In the Southern Anthracite field it is found over the coal mined 

 at Kohlers Gap; at the horizon of the roof of Lvkens coal No. 2, at the 

 North Brookside slope; and in the Pottsville Gap at the approximate 

 level of Lykens coal No. 3. A form of doubtful specific identity occurs 

 at a level supposed to be not far abo^•e that of the roof of L^dcens coal 

 No. 4 at the Kemble drift on Broad Mountain. 



Sphenophyllum cuneifolium (Sternb.) Zeill. 



As has already been noted in the discussion of the floras in the sev- 

 eral horizons of the Pottsville formation, two forms which appear to 

 be referable to this species occur in this formation. The first, which 

 is represented b}' the type figured ]^y Lesquereux in fig. 9, pi. xciii, 

 Vol. Ill, of the Coal Flora, is especial!}^ characterized by its slender, 

 narrow, lax form, thin, rather membranous texture, equal teeth, and 

 slender, fine nervation, the forking of which occurs mostly in the lower 

 part of the leaf. The second form may be briefly described as more 

 closely resembling the smaller, narrower, and often dissected leaves 



' Die Caliimarien rt. Schatzlarcr Seliichten, 1HS7. p.202, pi. xv, figs, la, lb, 4. 



