122 THE FLORA OF THE DAKOTA GROUP. 



base, more or less distinctly and acutely dentate, penninerved. Midrib 

 thick; secondaries, six to ten pairs, according to the size of the leaf, ol)li([ue, 

 parallel, equidistant, straight in ])assing to the borders, the lower pairs 

 ramose, with sometimes underneath a thin basilar simple or marginal pair 

 of nerves close to the borders. 



As I have done for the leaves described as Betulites, I refer most of 

 these to one species, with some variation indicated by an additional name. 



All the leaves have the areas traversed by distinct, simi)le nervilles, 

 more or less curved at the middle, about at right angles to the secondaries ; 

 the nervilles become often nearest to the borders, angularly plicate in the 

 middle and there joined to a vertical branch tending to the borders. The 

 petiole of these leaves is strong, straight, nearly 5''"' to G"" long, inflated and 

 curved at the base as in Betulites; the dentation of the borders is varied, 

 the teeth being sometimes sharp and distinct, sometimes scarcely marked. 



The leaves considered as essential varieties are iigured as follows : 



Viburnum Lesqueeeuxii var. commune, n. var. 

 PI. LIIl, Fig. 2. 



This is the form the more generally observed. Leaves small, truncate 

 or subcordate at base; basilar nervilles very thin, quite near the borders, and 

 simple; teeth of the borders distinct. 



Viburnum Lesquereuxii var. rotundifoliiim, n. var. 

 PI. LII, Fig. 8. 



Leaves nearly round; teeth regular, small, base broadly cuneiform; 

 secondaries oblique ; marginal none. 



Viburnum Lesquereuxii var. cordifolium, n. var. 

 PI. LII, Fig. 9. 



Leaves larger, more or less deeply cordiform at base, obtusely pointed 

 at apex, distinctly dentate; lowest secondaries nearly at right angles, none 

 simple and marginal. 



Viburnum Lesquereuxii var. longifolium, u. var. 

 PI. LIII, Fig. 1. 



Leaves large, cordate at base, long, tapering upwards to the obtusely 

 pointed ajjex; lower secondaries arched backward in passing to the borders, 



