DESCEIPTION OF SPECIES— KEAMNE^. 273 



PALIUEUS, Tourn. 

 P a I ■ K I' II s C o I o III b i , Heer. 



Plate L, Figs. 13-17. 



Paliurus Colombi, Heer, Arct Fl., i, p. 1'22, pi. xvii, fig. 2(J; xix, figs. 2-4; ii, p. 482, pi. 1, figs. 18, 19; 

 Sjiitzb. Mioc. Fl., p. G7, pi. xiv, lig. 11.— Lesqx., Aunual Report, 1871, p. 288; 1872, p. 388. 



Leaves oval, equally narrowed upward to an obtuse point and downward to a very short petiole ; 

 borders mostly entire, sometimes with one or two obtuse teeth ; lateral nerves in an acute angle of 

 divergence, carving inside, and anastomosing with secondary nerves or their branches toward the ijoint; 

 nervation camptodrome. 



These leaves are slightly smaller than those figured by Heer; but, other- 

 wise, they agree in all their characters; even, among the numerous specimens 

 from Carbon, some fragments represent leaves quite as large as those from 

 Greenland. All the large leaves have the borders entire; the small ones are 

 sometimes marked by one or two obscure or obtuse teeth, a character indi- 

 cated also in fig. 2dof pi. xvii of the Arctic Flora; all are sessile, or nearly so, 

 bearing only sometimes traces of a very short petiole (fig. 14 of our plate). 

 They are triple-nerved from the base, tlie lateral nerves branching outside, 

 ascending to above tlie middle, where they unite by branchlets to the sec- 

 ondary ones. These, generally few, three or four pairs, in the upper part of 

 the leaves curve in passing to the borders, which they closely follow parallel 

 to the branches, and anastomosing with them in simple festoons. One of tlie 

 specimens to the leaf represented in the Arctic Flora (pi. xxvii, fig. 2d) has, 

 not in connection, but in the direction of its base, a fragment of a slender, 

 apparently long, petiole. If the reference of this fragment to Paliurus is right, 

 the petiole is there casually out of place, or the leaf may represent the species 

 described before as Fopulus decipiens (p. 179, pi. xxiii, figs. 7-11), whose 

 leaves are so very similar by their shape and nervation that I considered 

 them at first, and frofti the specimen (fig. 7) deprived of a petiole, as repre- 

 senting the same species of Paliurus. This confusion is the more easily 

 made, since the specimens of both are found together, especially at Carbon, 

 where they are abundant. The difference is merely in the larger size and the 

 shape of the leaves of P. decipiens, which, generally wider in the middle, bear 

 a thin marginal veinlet from under the primary nerves, a character seen upon 

 fig. 3, pi. xix, of the Arctic Flora. The first description of this Paliurus (in 

 Annual Report, 1871, p. 288) was made from leaves of these two different 

 species. By the shape of the leaves and the nervation, this species is allied to 

 Ceanothus thyrsijlorux, Esch., of California. 

 18 T F 



