DESCEIPTION OF SPECIES— AMPELIDE^. 239 



They are apparently cuneate to an obtuse point or obscurely trilobate. Of 

 medium size, three-nerved from the base, they have the secondary veins and 

 their branches running to the borders, and effaced in joining them, and all the 

 nerves thin, though distinct, like the nervilles, which are close, simple, with a 

 net of square or equilateral meshes between them. 



Habitat. — Golden, Colorado, where I have found the specimens figured 

 here with other smaller fragments, none of them with the point of the leaf, 

 all identifiable by their membranaceous substance and their reddish, smooth 

 surface. 



Cissus Pai'i'Otiaerolia, Lesqx. 



Plate XL, Figs. 10-17 ; Plate XLII, Fig. 1. ' 



Cissus Parioii<Bfolia,hesq;s.,, Aunaal Report, 1874, p. 314. 



Leaves ovate, cuDeiforra to tbe base, sometimes rounded and subcordate, deltoid to the obtuse 

 point, equally and regularly undulate-crenate, three-nerved I'rom the top of the petiole; lateral nerves 

 divided in parallel, equidistant, straight branches, entering the obtuse divisions of the borders. 



The leaves are subcoriaceous, of medium size, averaging eight centime- 

 ters long, and five broad a little below the middle, abruptly, narrowed or 

 rounded to the petiole. Fig. 16 is a fragment with apparently the same 

 characters, but subcordate to the base. The two lateral primary nerves, 

 as thick as the midrib, and joining it in an acute angle of divergence a 

 little above the basilar border, ascend nearly straight to one of the border 

 divisions, which, a little more prominent than the others, gives to the leaves 

 a slightly trilobed form; these nerves are regularly branched outside, the 

 divisions equidistant, parallel, corresponding to the obtuse, short teeth entered 

 by them. In the figures of pi, xl, the secondary nerves are placed at a great 

 distance above the base; but far less so in fig. 1 of pi. xlii, which I was dis- 

 posed to consider, by reason of this difference, as a separate species. All 

 the characters of this leaf are, however, exactly the same; the identity of 

 shape is especially striking. I, therefore, admit it as a mere variety. The 

 areolation, distinctly observable in figs. 16 and 17, is, as in the former species, 

 composed of square areolae, intermediate to strong, mostly simple nervilles. 

 ^ Habitat. — The specimens of the figures on pi. xl are all from the Lower 

 Green River group, found in connection with Ficus arenacea, F. lanceolata, 

 Populus arciica, etc. The specimen represented in fig. 1 of pi. xlii is from 

 the coal-beds of Medicine Bow, Wyoming, found in connection with Platunus 

 GuillelnKe and Phragmiks CEningensis {Dr. F. V. Hayden). 



