292 UNITED STATES GEOLOGICAL SUEVEY— TERTIARY FLORA. 



fore, is the only one which might be described separately. As it was found 

 in specimens from the same locality, as also its lateral veins, mostly opposite, 

 have the same angle of divergence, are straight in passing to the borders, and 

 craspedodrome, it seems really to represent a leaflet of the same species. Fig. 

 5, with a longer petiole, is apparently the terminal leaflet of a compound leaf; 

 the smaller are the lateral ones. But it is not evident if Ihe subdivision of 

 the leaf is tripalmate or pinnate. Tiie comparatively large number of 

 small leaflets rather indicates their relation to a pinnate leaf This species 

 is comparable to Rhus Pyirhce, diflering by its nerves running straight to 

 the borders and directly entering the teeth, which, moreover, are much 

 larger in the European species. The specimen represented in fig. 4 of pi. 1 

 is a narrower leaflet, apparently referable to this species. 



Habitat. — Evanston, Wyoming. The specimen of this last figure is 

 from Middle Park, Colorado {Dr. F. V. Hayden). 



K Ii u s ni c ui b r a n a c « a , Lesqz. 

 Plate LXIV, Figs. 6, 7. 

 Rhus manbranacea, Lesqx., Annual Report, 1874, p. 306. 



Leaves ternate ; leaflets ineinbranaceous, oblong, or the lateral ones broadly oval, obtusely pointed 

 rounded or subtruncate to a short petiole, irregularly coarsely duplicato-dentate; Lateral nerves open, 

 craspedodrome, more or less ramified, the lowest ones curving downward in joining the midrib. 



The specimens represent one leaflet entirely preserved, longer and nar- 

 rower, like the terminal one of a tefnate leaf, and part of a lateral one, shorter 

 and broader. The first, two and a half centimeters long, including the petiole 

 (three millimeters), is oblong, with borders cut from the base in comparatively 

 large, obtusely pointed teeth, either simple or with smaller protuberances 

 upon the back; the nervation is distinctly craspedodrome, the secondary 

 veins passing up and scarcely curving to the point of the teeth, and irregidarly 

 obscurely dividing in thin branches, joined in the middle of the areas, con- 

 stituting large, indistinct areolae. By the ibrm of the leaflets and the 

 border divisions, this species is closely related to li. Pyrrha, Ung., as figured 

 by Heer (Fl. Tert. Helv., pi. cxxvi, figs. 20-28), whose leaves are round, 

 truncate at the base, and broadly dentate, as in our fig. 7. Like R. Fyrrhce, 

 it is also comparable to R. aroniatica, Ait., a common species of our present 

 flora, widely distributed over the whole width of the United States, and 

 whose leaflets, extremely variable, have also doubly dentate leeth, and, in tlie 

 Southern States, a membranaceous consistence. 



Habitat. — Point of Rocks, Wyoming {Dr. F. V. Hayden). 



