196 DESCRIPTION OF SPECIES. 



upper entering the teeth or lobes, all being obliquely short branched. The 

 relationship is also marked with the preceding species, which evidently 

 pertains to that peculiar and variable type of B. aromatica which is still 

 universally distributed in innumerable varieties through the North Amer- 

 ican continent from the 30° to the 43° of latitude. 

 Hab. — Florissant. Princeton Museum, No. 718. 



Rhus trifolioid.es, sp. nov. 



Leaves trilobate; leaflets oval; the medial slightly obovate and a little longer, 

 narrowed to a short petiole; the lateral sessile, all apiculate and dentate to the middle. 



The medial leaflet is 2£ centimeters long, 12 millimeters broad in the 

 middle, the lateral ones 2 centimeters long and 1 broad, not as distinctly 

 dentate as the middle. The teeth are sharp, turned exactly to the outside. 

 The leaf is comparable to E. Napcearum, Ung., "Syllog.," i, p. 43, pi. xx, 

 fig. 11, differing by the form of the oval sharply dentate leaflets. The 

 pedicel is broken 1 centimeter below the base of the leaflets, the nervation 

 indistinct. 



Hab. — Florissant. Lacoe's Collection, No. 58. 



Rhus rosae t'ol i a , Lesqx. 

 "U. S. Geol. Rep.," vii, p. 393, pi. xlii, figs. 7-9. 



ZANTHOXYLE^E. 



ZANTHOXYLON, Linn. 



Zanthoxylon spireae folium, sp. nov. 



Plate XL, Figs. 1-3. 



Leaves odd-pinnate ; leaflets ovate, acute, or blunt at the apex, obscurely serrate, 

 short-petioled ; secondary nerves at an acute angle of divergence, parallel, simple or 

 forking, camptodrome. 



The leaflets vary from 1* to 2i centimeters long and from 7 to 14 

 millimeters broad; the lateral nerves appear craspedodrome in fig. 1. But 

 in figs. 2, 3, where the veins are more distinct, they are seen joined to the 

 teeth by nervilles and camptodrome. 



This species is closely allied to Z. juglandinum and Z. serratum, Heer, 

 represented "Ft. Tert. Helv.," pi. cliv, tigs. 36 and 37. Upon the leaf, 



