DESCEIPTION OF SPECIES— RHAMKEJ^. 275 



ZIZYPHUS, MiU. 

 Zizyplius <l is tortus, Lesqz. 



Plate LI, Figs. 7-'.). 



Zlzyphus distorius, Lesqs., Annual Report, 1873, p. 404. 



Leaves membranaceous, very entire, rounded or truncate to the petiole, palmately five-nerved 

 from tlio base; midrib thick; lower lateral veins simple, following the borders, the inner ones stronger, 

 branching, curving inward and ascending higher up toward the point; nervation caniptodrome. 



The leaves vary in size from four to seven centimeters broad, and some- 

 what longer, the upper part being broken in all the specimens obtained. 

 The nervation is that of the leaves of this genus, represented with borders 

 entire, like Z. protohus, Heer, etc.; though, in most of the fossil species de- 

 scribed, it is generally simply three-palmate. The shape of the leaves slightly 

 inequilateral, and the nervilles very close, numerous, and simple, at right 

 angle to the nerves, are characters which relate them to Zizyplms. 



Habitat. — Golden, Colorado; rarely found, and always in fragments. 



Z I K y p li II s lU e c k i i , Lesqx. 

 Plate LI, Figs. 10-14. 



Zizyplius Meelcii, Lesqs., Annual Report, 1872, pp. 388, 389. 



Leaves subcoriaoeous, ovoid, obtusely acuminate or pointed, rounded to the petiole, obtusely cre- 

 nate, three- or five-nerved from the base. 



The leaves differ little in their size and their characters. They average 

 five centimeters in length and three in width; the borders are crenate or 

 creuulate from quite near the base to near the obtuse point, which, either 

 rounded or acuminate, is generally entire; the lateral outside primary nerves, 

 not always present, curve along the borders, and anastomose below the middle 

 of the leaves with branches of the internal ones; these ascend higher to the 

 point or to near the point of the leaves, are more or less branched like the 

 marginal ones, forming with their branches a simple series of bows connected 

 to the teeth by straight, oblique nervilles, as seen in figs. 11 and 12. The 

 fibrillse, rarely discernible, are at right angle to the midrib, somewhat oblique 

 to the lateral nerves, and close, mostly simple. This species is allied to Z. 

 ovatus, Web. (Palseont., ii, p. 203, pi. xxii, fig. 12; xxiii, fig. 1), whose leaves, 

 however, have the lateral nerves simi^le and more distinctly aerodrome. It 

 has a more marked relation to the following species, of which it looks hke a 

 diminutive form, and is comparable also by the shape of the leaves to Grewia 

 crcnata of Heer. 



