DESCKIPTION OF SPECIES. PP. 49 



Neuropteris Jlexuosa, Brongt. 



This plant is one of the most widely diffused and per- 

 sistent of all the Carboniferous flora. It ascends from tho 

 Vespertine, where, (as at Lewis Tunnel,) it is slightly modi- 

 fied, to the top of the Carboniferous system. In the upper 

 beds, it forms by far the most abundant plant, often exclud- 

 ing all others from certain localities. 



Plate yill. Fig. 6, shows a very singular form of this 

 species, which would, if found isolated, be taken for a dif- 

 ferent species ; but so many intermediate forms, connecting 

 it with the normal plant, occur, that it cannot be separated 

 from it. Tlie pinnules are very small, somewhat falcate, 

 and attached by all of the somewhat contracted and rounded 

 base. This form is found in the roof-shales of the Waynes- 

 burg Coal, at Carmichaels, Penna. 



Plate VIII, Fig. 1, shows a form of flexuosa, which dif- 

 fers from the normal type sufficiently to constitute a variety 

 at least. This may be styled : Neuropteris flexuosa^ var. 

 longifolia. It is distinguished from the typical forms of 

 the species, by having much longer pinnules, which, are also 

 opioosite, a feature not seen in N. flexuosa, or indeed com- 

 monly in Neuropterids. It is not a new species, for we 

 find intermediate forms connecting this with the normal 

 type. 



Habitat. — Roof-shales of the Waynesburg Coal, West 

 Union, W. Va., with great numbers of the normal form. 



Neuropteris dictyojjteroidcs, Sp, nov., PL VIII, Figs. 

 3-6. 



Frond, pinnate or bipinnate ; pinnules, alternate lanceo- 

 late, with cordate base, and attached by a cordate base to 

 a rather stout rachis ; mid-nerve, very broad and appear- 

 ing to be made up of parallel adjoining nerves, which are 

 formed by the union of the lateral nerves, pioducing a flat 

 ribbon-like bundle ; lateral nerves, dichotomizing in passing 

 to the margin as usual in Neuropteris, very fine, and rather 

 indistinct in their course, sending off delicate thread-lilve 

 branches which anastomose with the adjoining lateral nerves, 

 at an acute angle and forming elongate meshes. 

 4 PP. 



