''''is'jo"''] PROCEEDINGS OF THE NATIONAL MUSEUM. 283 



Assocuited with these stems are the casts of many hirge and small 

 stems of Equisetam ; but the matrix is by far too coarse and granular 

 to successfully preserve delicate leaves or frouds. 



DESCRIPTION OF THE SPECIES. 



By TVm. M. Fontaine. 



I. — Plants of the lower horizon or from the iieic copper mines. 

 Equisetum Abiquiense sp. no v. Fontaiue. Plate xxii, fig. 1. 



This is ])reserved in a coarse white sandstone. It is characterized by 

 the considerable width of the ribs, their flatness, and the great number 

 and distinctness of the scars left by the articulation of the leaves. The 

 larger piece must have formed a part of a stem G inches in diameter. 



This fossil, forming cast N'o. 1, is much like Schizoneiira planicostata., 

 Rogers spec, the Calamlfes planicostatus of the Richmond coal field, and 

 may be the same plant. As, however, no impressions of Schizoneura 

 have been found in this formation, and as the other fossil found with it 

 is certaiidy an Equisetum, it seems best to regard this as an p]quisetum 

 also until portions more decisive of character are found. For conven- 

 ience of reference it may be called Uquisefum Abiquiense. Two speci- 

 mens, internal casts. 



Equisetum Knowltoui sp. nov. Fontaine. Plate xxiii, Figs. 2-4. 



This cast is preserved in a tine grained white sandstone. The casts 

 on their exterior are usually impregnated with malachite, the carbona- 

 ceous matter seeming to have been active in precipitating the copper 

 from solution. These impressions evidently were formed by a plant 

 very different from that yielding cast No. 1. 



These casts are characterized by the possession of numerous very 

 short internodes, very narrow prominent ribs, and by the entire ab- 

 sence of the scars of leaf-articulations. The shortest internodes are 1 

 centimeter in length, one specimen (Fig. 4) showing six of these. The 

 longest are 22 millimeters in length. The widest ribs are 1 millimeter 

 in breadth and the narrowest about one-third of a millimeter, and the 

 average is about one-half of the same. In the narrowness of the ribs 

 this plant resembles the internal casts of Equisetum Rogersi of the Rich- 

 mond Coal Field, the impressions that were called Calamites arenaceus. 

 The persistent shortness of the internodes, however, is a feature which 

 distinguishes this from the Virginia plant. It might be called Equi- 

 setum Knowltoni. Six specimens ; internal casts. 



II. — Plants of the upper horizon or from the old copper m^ines. 



As Mr. Knowlton points out, the plants of this higher horizon are 

 totally different from those lower down. I find among them none of the 

 imi^ressions of Equiseta that form all of the fossils of the lower horizon. 



