16 /.■ I \inct Floras of North America^ 



confounded, though bearing some resemblance to A. integer- 

 rimus (Viv. M>-: , Greol. France, L833, vol. L, p. L33, tab. 



xl. : In that species, however, the lobes are narrower and 



more elongated. Fourspecies of Ac rites have been described 

 from the Cretaceous strata of Europe. Of these I have only 

 the descriptions of two, A. repandus and A. styracifoUus ting., 

 both of which are quite different from this. 



Formation and Locality. Lower Cretaceous Bandstone, 

 ckbird Hill, Nebraska. (Dr. Bayden.) 



Poi>uliis ellipfica. (n. Bp.) 



I. avea long— petioled, sub-orbicular or transversely elliptical, 

 slightly cuneate at the base, and apiculate at summit; lower half 

 of leaf entire ; superior half, or more, very regularly and rather finely 

 olii 11^1 1\ serrate, or crenate, the points of the teeth inclining upward ; 

 primary nerves usually •"». BometimeB 3, radiating from the base at 

 .1 angl< ; from these the secondary nerves spring at acute 



This is an exceedingly neat and well-defined species, very 

 fully represented in \)v. Eayden's collections. Ii is symmetri- 

 cal in form, broader than high, forming a transverse ellipse, 

 from the opposite Bides of which rise the corresponding and 

 equal projections o'f the apiculate summit, and Blightly decur- 

 reni base. The crenation of the upper portion of the leaf is 



. regular and neat, the teeth of small size, and turned up- 

 ward. The general aspeel of the leaf is ool very different from 

 thai of some specimens of /'. tremuloides, bul the cm ire mar 

 >/\u- at the lower half of the leaf, the more elliptical outline, 

 shorter point, and larger and more regular teeth, mark its 

 specific differences with sufficient distinctness, while the cor- 



iondence which the leaves of the two species present, in the 

 creneral characters of form, nervation and crenation, affords 

 Batisfactoi'3 evidence of generic identity, and apparently bears 

 unquestionable testimony to the existence, at the dawn of the 



