MUSEUM OF COMPAKA.TIVE ZOOLOGY. 55 



Rhamneae. 



99. Paliurus Zizyphoides, Lx. 2 specimens. 



100. Paliurus tenuifolius, Heer. Leaf small, membranous, ovate, acute, 

 entire to near the apex, where it is marked with a few acute small teeth ; lat- 

 eral nerves parallel to the borders up to near the apex, where they join the 

 secondaries by anastomosing branches ; secondaries opposite, at a great dis- 

 tance from the primaries. 



The leaf has the characters of the species as described and figured by Heer, 

 Fl. Tert. Helv., III., Plate CXXII. fig. 31, and by Saporta, Ett., I. p. 122, 

 Plate XII. fig. 5. Heer, however, says of the leaves that they are very en- 

 tire ; but the upper part of the leaf figured by him, loc. cit., is destroyed, while 

 Saporta describes the leaves as subundulate-denticulate. The one which I 

 refer to this species, considering it a mere variety, is preserved nearly entii-e. 

 1 specimen. 



101. Paliurus Coloradensi.% sp. nov. Leaf small, obovate, obtuse, denticu- 

 late above, triple nerved from above the base, with a single pair of opposite 

 secondary veins above the middle of the leaf, parallel to the basilar ones, 

 aerodrome and branching outside. 



The top of the leaf is somewhat obliterated ; its nervation is much like that 

 of P. ovoideus, Heer, Fl. Tert. Helv., Plate CXXI. figs. 58, 59, Plate CXXII. 

 fig. 3. Its size is intermediate between that of figs. 58 and 59. But it greatly 

 differs by its obovate form and the position of the intermediate pair of sec- 

 ondary nerves, as thick as the primaries and parallel to them. 1 specimen. 



102. Zizyphus fibrillosus, Lx., U. S. Geol. Surv. of the Terr., VII. p. 276, 

 Plate LII. figs. 1-6. The specimens of this species are fine, and the petiole 

 of one of the leaves is preserved 2 cm. long. The base of the leaves is either 

 round, subtruncate, or subcordiforni. The largest leaf is nearly 10 cm. long, 

 and 7 cm. broad in the middle. 7 specimens. 



103. Zizyphus hyperboreus, Heer. The leaf is like that described in U. S. 

 Geol. Surv. of the Terr., VII. p. 276, Plate LI. fig. 15, doubtfully referred to 

 Heer's species described from Greenland specimens. The texture of the leaf 

 is coarse, the nerves very prominent ; the nervilles uniting the lateral nerves 

 to the borders are at right angles, thick, and the medial nerve has two pairs 

 of branches in the upper part. 3 specimens. 



104. Zizyphus, sp. undeterminable. 1 specimen. 



105. Ehamnus Goldianus, Lx. 13 specimens. 



106. Rhamnus Cleburni, Lx. 7 specimens. 



107. Ehamnus crenatus, sp. nov. Leaf large, ovate-lanceolate, acuminate, 

 rounded or subcordate at the base (broken), minutely crenate ; lower lateral 

 nerves more open, the upper gradually more oblique, all much curved in pass- 

 ing toward the borders, and inclining to the midrib ; the two highest pairs 

 aerodrome ; nervilles numerous, close, parallel. 



This fine leaf is 12 cm. long (base and apex broken), 6 cm. broad a little 

 above the base. It has the same form, size and nervation as R. grosse-serratus, 



