130 THE LATER EXTINCT FLORAS OF NORTH AMERICA. 



carrying' one to two branches at the summits, the upper ones simple, all 

 terminating in the marginal teeth; tertiary nerves numerous, connecting 

 the secondaries nearly at right angles, and generally parallel." 



Collected by Dr. F. V Hayden. 



The nervation of these leaves is strong, regular, and crowded. The 

 marginal serration is simple, coarse, and sharp, much like that of the leaves 

 of many species of Viburnum. 



Formation and locality: Tertiary (Fort Union group). Fort Union, 

 Dakota. 



Viburnum cuneatum Newb. 



PI. LVII, fig. 2. 

 Proc. U. S. Nat. Mus., Vol. V (March 21, 1883), p. oil. 



"Leaves petioled, long-obovate, 10 centimeters or more in length by 

 4 centimeters in width; margins entire below the middle; above, set with 

 coarse sub-acute or acute teeth; nervation strong, simple; midiib straight, 

 giving off at an acute angle seven or eight simple, strong nerve branches 

 on either side, which terminate in the teeth of the margin." 



Collected by Dr. F. V. Hayden. 



The general aspect of this peculiar leaf is as much like that of Cornus 

 as Viburnum, and if the basal portion alone were shown, few botanists 

 would doubt the propriety of referring it to Cornus. But the upper part 

 of the leaf is very strongly dentate, the simple strong nerve branches 

 terminating in these teeth, a character unknown in the species of Cornus, 

 living or fossil. Some species of Viburnum exhibit a somewhat similar 

 nervation and the dentate margin is much more in character here than in 

 Cornus. It has been thought best, therefore, to refer it provisionally to 

 Viburnum, a genus which seems to have been quite prevalent in late Cre- 

 taceous and Tertiary times on this continent, running into a great number 

 of distinct species. 



It is true, however, that the lateral nerves in the leaves of Viburnum 

 are always branched, though in some specimens of Viburnum dentatum per- 

 haps only one or two of the branches in a leaf give off branchlets. The 

 dentation is quite that of V. dentatum. Further collections, which will 

 undoubtedly be made in the region where this leaf was found, will doubt- 

 less determine to which of these genera these belong, the counterbalancing 



