67 

 Fagus polyclada, Lesqx., PI. v, Fig. 6. 



Leaf ovate-oblong, cuneate to the base, short-petioled ; borders entire and undulate ; medial nerve 

 straight ; secondary veins close, numerous, simple, parallel, craspedodrome. 



Fagus polyclada, Lesqx., American Journal of Science and Arts, (?), xlvi, 

 1868, p. 95. — F. cretacea, Newby.(!) Extinct Floras, p. 23. 



Leaf membranaceous, about 8 centimeters long, (the point is broken,) 

 including a short petiole 4 millimeters long, ovate-oblong, apparently obtuse, 

 with borders entire and regularly wavy, especially in the upper part ; media] 

 nerve straight and narrow; secondary veins oblique, in an angle of diver- 

 gence of 40° close to each other, 12 pairs in a length of 6J centimeters, very 

 thin, exactly parallel, running to the borders without marking them with any 

 denticulation. This last character appears to be the only essential difference 

 between this leaf and the one described by Dr. Newberry as F. cretaeea, 

 which, as he remarks, has the termini of the nerves most prominent, and the 

 intervals between them forming shallow sinuses. In our leaf, the secondary 

 veins are, on the contrary, effaced to the borders, and they indifferently end 

 either at the convex or the concave part of the undulations. 



The relation of this leaf to the genus Fagus is undeniable. In com- 

 paring it with some leaves of Fagus sylvatica, L., of Europe, it is scarcely 

 possible to point out any difference, except, perhaps, in the more numerous 

 secondary veins, and the more acutely wedge-shaped base. The living 

 species also has, in its leaves, the two characters which mark the differ- 

 ence between both the Cretaceous leaves described ; one with entire wavy 

 borders, the other with the borders denticulate by the short protraction 

 of the point of the veins beyond the borders of the limb. This last character 

 is more distinct in our Fagus ferruginea, Ait., considered for a long time as a 

 mere variety of F. sylvatica. We have, therefore, in these two leaves exact 

 representatives of the only species of beech now living in the northern regions, 

 of both the American and the European continents. Counting eight doubtful 

 species, Schimper describes, in his Pal. Veget., twenty-three species of Fagus, 

 all Tertiary except the two mentioned here from the Dakota group, and 

 one unsatisfactorily known, from arenaceous concretions of Austria and 



Hungary. The Tertiary sjiecies are without relation to our Cretaceous 

 leaves ; they have dentate or serrate borders, except Fagus dubia, Wat., 



represented by a fragment which does not even appear to belong to a spe- 

 cies of Fagus, and F. macrophylla, Ung., whose leaves are very large, 18 cenli- 



