DESCKIPTION OF SPECIES. 73 



Emmons's plant seems to differ from that of Schenk only in the slightly- 

 greater width of the leaflets, and their greater closeness. In these points it 

 comes nearer, perhaps, to the plant from the Oolite of England, described 

 as Pterophyllum Presternum, Bronn, "Lethsea Geognostica," plate xiv, fig. 10, 

 which is identified by Bronn and Schimper with Zamites pecten, of Lind. 

 and Hutton. Emmons's Pterozamites gracilis, fig. 86, and his Dioonites 

 linearis, plate iv, fig. 11, also belong to Ctenophyllum Braunianum. 



The portion of the plant given in Plate XXXIV, Fig. 4, from the base 

 of the leaf, with leaflets at right angles to the stem, much resembles Hugh 

 Miller's fig. 133, of what he calls a Zamia, in his "Testimony of the Rocks." 

 Miller's plant comes from the Upper Oolite of Helmsdale, Scotland. 



Formation and locality. — Found at nearly all the plant localities in the 

 Richmond Coal Field, both from below and above the main coal seam. 

 Especially abundant above the main seam at Carbon Hill, in gray shale. 



Ctenophyllum grandifolium, spec. nov. 



Plate XXXIX, Figa. 1-3; Plate XL; Plate XLI; Plate XLII, Fig. 1. 



Leaf very large, over a meter in length and more than half a meter in width. 

 Midrib very broad, flat, and fleshy in texture, smooth, with a very thick, firm epider- 

 mis, which conceals the bases and the insertions of the leaflets, and causes it to 

 appear wider than it really is. Leaflets in the lower part of the leaf, inserted at a 

 right angle, remote, and of unequal widths, in the middle and upper portions more 

 uniform in width and more closely placed, those of the middle portion of the leaf goiug 

 off at an angle of 45° or one somewhat greater, separate to the base, becoming more 

 and more oblique in insertion towards the upper part of the leaf, and united at their 

 bases towards the summit of the leaf. They are over 30 centimeters in length, and from 

 10 to 12 millimeters wide in their middle portions, strap-shaped, and of the same width 

 to near their bases, where they are gradually narrowed until the base is reached; 

 here they are slightly expanded at their insertions, so as to be pro- and decurrent on 

 the stem. The nerves are very strong and distinct, standing out like threads; they 

 fork at, or near, the base, the branches diverge very slowly and then run parallel to 

 one another and the margin of the leaflets. As seen under a lens, and sometimes 

 without it, the apparent simple nerves are composed of two nerve-strands, so closely 

 placed as to form a nerve-bundle which appears to be single. The leaflets appear to 

 have been thick and firm, and to have had a dense epidermis. 



I have been somewhat at a loss where to place this magnificent plant 

 in the existing genera of cycadaceous plants. It is a good deal like the 

 plants that Schimper puts in the genus Macropterygium, which are found in 



