FLORA OF THE DAKOTA GROUP. 69 



top mid undulate by the out-running of the veins. II is triple-nerved 

 from a distance above the base, and has above the point of connection 

 of the primary nerves two or three pairs of alternate secondary veins, 

 variable in distance, straight or curved, unequally parallel, reaching the 

 borders cither directly or by their branches, which by oblique branchlets 

 or by connections of nervilles at right angles form irregular quadrate large 

 meshes. There are under the primary nerves two pairs of marginal veinlets 

 with the same degree of divergence as the primary ones (40°-50°). The 

 form of this fine leaf and its mode of nervation are peculiar, and of a 

 character analogous to that of leaves described under the generic name 

 of Greciojw's in the ''Sezanne Flora" by Saporta. There is, however, a 

 marked difference in the primary ternate nervation and in the en 'ire 

 borders of the leaves. The two lower pairs of tertiary veins show also for 

 this leaf a relation to Qredneria, and especially to the small leaf of Platanus 

 Ileerii, pi. iii, fig. i. The secondary and tertiary nerves are of a different 

 character. 



Hah. — South of Fort Harker. CJis. Sternberg. 



Amp elopli villi in ova turn, Lesqx. 



Hayden's "Ann. Kep.," 1874, p. 355. 



Celtist ovata, Lesqx., "U. S. Geol. Kep.,'' p. 06, pi. iv, figs. 2, 3. 



Leaves ovate, obtuse or undulate, truncate or obtusely pointed, enlarged toward 

 the base aud abruptly rounded and sub-truncate or cordiforin at base; nervation trind 

 from the base, craspedodrome. 



Though the relation of these leaves to the preceding species is not 

 very distinct, it is, however, more marked than to the leaves of Celtis. 

 But for the craspedodrome, and especially the ternate primary nervation, 

 they might be referable to Populus or Populites, having indeed some degree 

 of affinity to P. elegans, Lesqx., " U. S. Geol. Rep.." vi, pi. iii, fig. 3. 



HAMAMELIDEiE. 



HAMAMELITES, Sap. 



Leaves membranaceous, glabrous, petiolate, oblong-lanceolate or ovate; nerva- 

 tion pinnate; secondary nerves at an acute angle of divergence, craspedodrome. 

 branching on the lower side; branches and subdivisions generally camptodrome. 



The leaves described in this generic division have the essential char- 

 acters of the leaves of both Hamamelis and Alnus. 



