192 DESCRIPTION OF SPECIES. 



to see whether this small nut is costate. Therefore, as in the two preced- 

 ing species, the reference is uncertain. 



Hab. — Florissant. Princeton Museum, No. 709. 



PTEROCARYA, Kunth. 



Pterocarya Americana, Lesqx 



" U. S. Gcol. Rep.," vii, p. 290, pi. Iviii, fig. 3. 



ENGELHARDTIA, Leschen. 



Leave.s abruptly pinnate; leaflets unequilateral, generally resiuose, punctate on 

 the lower surface; primary nerves .strong, secondary tUiu, caiuptodrome, anastomosing. 

 Flowers agglomerated iu paniculate ears; drupe small, connate at base to a tri-alato 

 involucre; dorsal lobe generally absent (in fossil speduiens), epicarp coiiaceous, puta- 

 men bicostate. 



Eng-elhardtia oxyptera. Sap. 

 "Et.,"ii,p.344,pl.xii, fig. 2. 



Lobes of the involucre linear-oblong, obtusely pointed, the lateral half as long as 

 the middle; medial nerve distinct to the point, the lateral open-oblique, camptodrome. 



The involucre from the base of the nucleus to the top of the medial 

 lobe is 3 centimeters long, a little more than 2 to the top of the lateral 

 ones. The basilar nervation of the middle lobe is in two short basilar 

 parallel nerves and above in curved secondary nerves, as in the lateral 

 lobes; all the nerves are camptodrome and anastomosing. The involucre 

 is only slightly larger than in Saporta's figure ; the nervation is the same. 



Hah. — Florissant. Wm. Cleburne. 



anacardiacej:. 



RHUS, Linn. 

 "U. S. Geol. Rep.," vii, p. 291. 



Blius fraterna, sp. nov. 



Plate XLI, Figs. 1,2. 



Leaves simple, submembranaceous, long-petioled, rhomboidal-oval, equally nar- 

 rowed to the acute apex and to the petiole, very entire; medial nerves narrow, the 

 lateral thin, nearly parallel, oblique, much branching, and obliquely reticulate toward 

 the borders. 



The leaves average 4 centimeters long and 2 broad in the middle, the 

 widest part. The nervation is delicate but very distinct; the secondary 



