194 DESCRIPTION OF SPECIES. 



The nervation is like that of some species of Cassia — C. lignitum, C. amhigua, 

 Ung., for example. 



iTai.— Florissant. U. S. Geol. Expl. Dr. F. V. Hayden. 



Rhus Hillia;, sp. nov. 

 Plate XLI, Figs. 13-15. 



Leaves irregularly piiinately divided; terminal leaflets large, pyramidal, more or 

 less rapidly narrowed to the base, deeply irregularly dentate; lateral pinnules small, 

 nearly at right angles, ovate, acute, dentate, alternate or opposite, subdecurrent, sessile. 



These leaves, which seem to have been compound and odd-pinnate, 

 are represented in the fossil state merely by the terminal pinnules and 

 one or two of the lateral ones attached to one side of their base, figs. 13, 

 14, or one pair opposite and sessile on the rachis at a distance from the 

 terminal pinnule, fig. 12. The nervation is distinct. As seen in fig. 13, the 

 secondary nerves are very oblique, straight, with intermediate shorter ter- 

 liary veins and nervilles at right angles. 



The species is comparable to Rhus incisa, Sap., "Et.," iii, 1, p. Ill, pi. 

 ii, fig. 4, which is made of a single small leaflet similar to fig. 15 of our 

 plate. 



Hah. — Florissant. Fragments and pinnules of this species have been 

 seen in all the collections made by Mrs. Hill. 



Rhus acumiuata, Lesqx. 

 PI;ite XLII, Figs. 14-17. 

 Lfsqx , f^ii|i|il. Id IlavdiMis 'Aiiii. IIi'p.," ISri, p. 8. 



Leaflets luurowly ovate, lanceolate, acnmiuate; borders deeply dentate from near 

 tlie base; lateral nerves open, joining the midrib nearly at right angles, much curved, 

 craspedodrome. 



These leaflets have great analogy of character with the terminal leaf- 

 lets of Weinmannia as seen in pi. xlii, fig. 3. They cannot be referred to 

 this genus, however, as they are contracted at base to a narrow not winged 

 petiole. Their relationship also, considering them as mere leaflets either 

 terminal or lateral, is with the preceding species, being by their shape, 

 the teeth of the borders and the nervation, intermediate between this and 



