868 FLORAL ZONES OF THE POTTSVILLE FORMATION. 



NOTES ON CERTAIN OF THE PREVIOUSLY KNOWN SPECIES, AND 

 DESCRIPTIONS OF THE STRATIGRAPHICALLY MOST IMPORTANT 

 FORMS. 



AXEIMITES roTTSVILLEN'SIS Sp. HOV. 



PI. CXC, Figs. 1, 2. 



Fronds lax, bi- or tri- ( () pinnate; pinna? slender, .slightl\' tlexuose or 

 sul)geiiic'ulate, loose, slighth^ irregular, with very slender, sulcate, 

 lineate, narrowly bordered {() rachis. 



Pinnules alternate, distant, open near the base, oblique above, poh'- 

 morphous, usually asymmetrically ovate or rhomboidal-ovate, some- 

 times obovate, obtuse, T to 18 mm. long, 3 to 11 mm. wide, the lower 

 ones neuropteroid or even triangulo-semicircular, the terminal pin- 

 nules cuneate-obovate, generally broad and truncate-rounded, the 

 lowermost sometimes dissected to the base to form 3'oung pinnje of 

 three pinnules, of which the middle one is similar to the ordinary ter- 

 minal ones, the lateral being rhomboidal, all the pinnules being con- 

 stricted to a verj^ narrow point of attachment, with straight proximal 

 margins, and very hnely lineate lamina between the nerves. 



Nervation a little coarse, radiating flabellately from a single basal 

 fascicle, forking three to live times while passing straight to the border, 

 and counting about 25 to the centimeter along the distal margin. 



The most common form of pinnule met in the fragments of this 

 polymorphous species is the rhomboidal type, such as is shown in PI. 

 CXC. Fig. 2. which represents the normal lateral pinnule. In this 

 illustration, which will })e supplemented by others in the larger work, 

 th(> characteristic rhomboidal shape is very imperfectly shown. The 

 sides, especially the superior proximal and the inferior distal margins, 

 are in general nearly parallel. The distal angle is nearly always well 

 markedexcept in the terminal pinnules, which are cuneate and roundly 

 truncate. An example of the last is seen in PI. CXC, Fig. 1. 



Of the species heretofore published, that to which our species is 

 most similar and most nearh' related is Aneimites adiantoides (L. and 

 H.) Ett. The extremely close affinity of these two forms may l)e 

 H'adilv noted )>v a comparison of the original tigure of S.ph<nu>pferh 

 adiantouh's^^ or that (Uvscribed })y Sauveur'~ as SpheiwjJterls o7>f(/siJoba, 

 with the specinicns in hand. 



Tlic Pottsville })laMt seems to be distinguished from the fern from 

 the elarrow colliery l>y its more rhomboidal and angular lateral pin- 

 nules, the less dilated or capitate terminals, and, to judge from the 

 ligure in the Fossil Flora, by the rather closer, more rigid nerva- 

 tion. One of the specimens from llie Culm, figured bv Dr. Stur as 



1 Lin<lli.-y ct Hulton, Kcww. Fl. (it. Brit.. Vol. II. pl.c.w. 

 - Vi'K- foss. terr. liuiiill. BelKique, pi. xxv. 



