FOSSIL PLANTS. 391 



ODONTOPTERIS SCHLOTHEIMII, Brgt. 



Veg. foss., p. 256, pi. 78, fig. 5. 



Rarely found in the concretions of Mazon creek, but abundant in the roof 

 shales of the coal at Morris. The frond of this fern is very large, at least tri- 

 pinnately divided; the alternate secondary pinnje linear lanceolate, two inches 

 long or more, and more or less deeply and regularly cut in alternate round, ob- 

 long lobes, or in oval-lanceolate obtusely pointed pinnules, varying from one- 

 fourth to half an inch long. The veins and veinlets, with the disposition and 

 divisions as marked in Brongniart's description, are thick, parallel, and gener- 

 ally forking once. In the large leaflets there is a medial depression looking 

 like a medial nerve, the veins generally branching from a medial point. 

 Though somewhat obscure, the specimens or this species at Morris are easily 

 identified by the reddish-brown color of the epidermis. 



GENUS ALETHOPTERIS, Sternb. 



This genus is admitted, for the disposition of the fronds and for their divi- 

 sion, as it is characterized by Goppert in his Systema, p. 175, and for the 

 position and the form of the fructifications, as modified by Geinitz.in his Ver- 

 stein, p. 27. It therefore contains not only species whose fructifications are 

 marginal and continuous, but species also bearing in some division of their 

 veins, or between them, round or starlike groups of sporanges like those of the 

 genur Asterocarpus, Gopp. As the fructification of some of our species is 

 unknown, or is not clearly seen through the substance of the leaves, some are 

 admitted into this genus from mere analogy in the divisions and in the form 

 of their fronds, and in their nervation. 



ALETHOPTERIS MAZONIANA, Sp. nov. 



PI. ix, fig. 1 to 8, and PI. xiii, fig. 5 and 6, fruiting. 



FROND evidently large, many times pinnately? divided, dicho- 

 tomous at the end of the divisions; pinnae long linear, taper- 

 ing slightly toward the points, either pinnately or bi-pinnately 

 lobed; lobes oblong entire obtuse, joined near the base and per- 



