EXPLANATION OF PLATES I. AND II. 409 



sight to be three-ribbed, the central nerve or mid-rib being 

 straight, and the one on each side curved, so that if pro- 

 longed they would meet the central one at the point were 

 the impression complete. There are, however, in fact seven 

 nerves springing together from the footstalk, the lower 

 pair having less prominence and more the character of the 

 secondary veins ; the next pair are but little smaller than 

 the three principal ones. On the upper surface of the 

 lamina the main veins were concave, while the impressions 

 of their under surfaces are sharp and rectangular. The 

 secondary veins and ultimate reticulations were prominent 

 on both sides of the leaf. The minute areola? are plain 

 and smooth, and there is no indication of any pubescence 

 in the axils of the veins. 



Impressions of leaves from the coal beds of the Raton, 

 in lat. 37^° N, long. 104^° W., (vide New Mexico by 

 Emery, Abert, Cooke, and Johnston, p. 522., plate), re- 

 semble this species, but are too imperfect for identifica- 

 tion. 



No. 5. 



An impression of a smaller leaf than the preceding is so 

 like it in the character of the veins, ultimate reticulations, 

 and general surface, that, but for a little difference in the 

 crenatures of the margin, they might be pronounced without 

 hesitation to be of the same species. The outline is sub- 

 rotund, transverse at the base near the footstalk, and appa- 

 rently entire there, crenated more irregularly and with 

 generally smaller teeth than the preceding on the sides ; 

 and entire near the tip, which is deficient in the specimen. 

 The diameter of the lamina of this specimen is an inch and 

 a half. It exhibits none of the round dotted depressions, 

 but there are some of the irregular clusters of little pits 

 on different parts of the surface which exist in the speci- 

 men figured in Plate II. and in some other casts. 



