DESCRIPTION OF SPECIES— NELUMBON^. 253 



one side; none of Ihem either lias dicliotomous divisions, and tlnis the leaves 

 of this species seem far different from those of our time, as also from those 

 described from the European Tertiary. In the small leaves of JV. luteum, 

 the nerves, twice as numerous as in this species, have also a tendency to turn 

 on each side toward the midrib; this character is not remarked upon the frag- 

 ments of figs. 1 and 2, though it is distinctly so in the better preserved leaf 

 of fig. 3, which I consider as a different species. 



Habitat. — (jolden, Colorado {Rev. Arthur Lakes). 



IVelumbium tenni folium, Lesqz. 

 Plate XLVI, Fig. 3. 



Nelmnhium tenui/olium, Lesqx., Aunual Report, 1873, p. 402. 



Leaves of a thin texture, comparatively small, eight to nine centimeters in diameter, orbicular, 

 peltate from the middle, with flat, undulate borders ; primary nerves thin, equal and equidistant, curved, 

 simple or sparingly branching, crossed at right angle by nervilles, craspedodrome. 



The essential differences between this and the former species consist in 

 the thin substance of the tissue of the leaves, the narrower veins, the borders 

 fiat, not recurved, the surface smooth or not roughened by the nervation. 

 The number of the nerves, thirteen, instead of fourteen, cannot be considered 

 as of any marked importance. In all the species, either living or fossil, known 

 until now, the primary nerves are dichotomous in their division, a character 

 at variance with that of the nervation of the former species, and which might 

 suggest some doubt in regard to the relation of these leaves to Nelumhium. 

 As we do not have in Europe any species of this genus from the Eocene 

 period, we may have here the earliest representative of a new type, whose 

 leaves may not have as yet reached their full development. But even in 

 this fig. 3, we see either simple nerves, or a few branches diverging from the 

 midrib, as in the coiflmon nervation of the dicotyledonous leaves, or dividing 

 at the top by an exact dichotomous division, as seen by two of these nerves. 

 Moreover, we have here, on the left side, a straight nerve like a midrib, toward 

 which the lateral veins curve, or rather a back nerve, as in N. luteum, in right 

 line with the midrib to the point of which the lateral veins tcxke their direc- 

 tion. In our living species, the two nearest nerves to this back vein often 

 curve, and reach its point by their ends. I do not think, therefore, that the 

 reference of these leaves to Nelumhium is contestable. In regard to the 

 possible identity of these three leaves, it could scarcely be admitted. The 

 great difTerence in their substance seems sufficient to authorize a separate 

 specification, though, in the examinotion of numerous leaves of iV. lutcum, 



