KNowLTON.] DESCRIPTION OF SPECIES. 35 
pair arching around and passing* toward the apex, other pair dividing 
the distance between the second pair and the margin, all apparently 
craspedodroine and forking; finer nervation not preserved. 
This fine leaf is the only specimen found. It is, fortunately, nearly 
all preserved, lacking only the apex and a portion of the margin of one 
side. In outline it is obovate or nearly elliptical, being 7.5 cm. in length 
and 4.5 cm. in width, without the petiole, which is not preserved. It is 
rather abruptly wed ge- shaped. The nervation consists of four palmately 
arranged, occasionally forked, ribs. 
I have been somewhat in doubt as to the proper generic reference of 
tli is leaf. It has, for example, some affinity with certain Dakota 
group species of Hedera, but on the whole seems more like Populus, 
being in shape quite like P. nervosa elongata Newb., but differing much 
from that species in nervation. 
This is of the more ancient type of the genus, that having the 
palmate nervation. 
The specimen was found by Prof. W. C. Knight, of the University 
of Wyoming, and is now preserved in the museum of the university. 
It comes from the lowest fossiliferous horizon at Harpers, being asso- 
ciated with numerous Fort Pierre invertebrates. It occurred in a 
nodule, and was the only plant observed. 
Habitat. — Harpers Station, Union Pacific Railroad, Wyoming. Col- 
lected by W. C. Knight. 
POPULTJS MELANARIOLDES Lx. 
Populus melanai'ioides Lx.. Bull. U. S. Geol. and Geog. Surv. Terr., Vol. I, p. 379 (1875) ; 
Ann. Rept. U. S. Geol. and Geog. Surv. Terr., 1874, p. 302 (1876) ; ibid., 1876, p. 507 
(1878) ; Tert. Fl., p. 147, PL LXII, fig. 5 (1878). 
Populus melanaria Heer, Fl. Tert. Helv., Vol. II, p. 16, PI. LIV, fig. 7; PL LVII, 
fig. 1; Lesquereux, Pull. U. S. Geol. and Geog. Surv. Terr., Vol. I, p. 370 (1875); 
Ann. Rept. U. S. Geol. and Geog. Surv. Terr., 1874, p. 302 (1876); ibid., 1876, 
p. 507 (1878) ; Tert. FL, p. 173, PL LXIV, fig. 5, (1878). 
The leaf described and figured by Professor Lesquereux under the 
name of Populus melanaria Heer is preserved in the United States 
National Museum. The type of P. melanarioides Lx. does not appear 
to have ever been in the National Museum, and its present location is 
unknown. The species, however, is represented by several fragments, 
one of which was obtained by Professor Ward from the type locality. 
The type and only American specimen of P. melanaria Heer, as 
shown by the figure of it in Tertiary Flora (PI. LXIV, fig. 5), is a mere 
fragment, showing only the lower part of the leaf with the petiole. 
The margin of this fragment is to be made out in one place only, and 
even here with some question. If what appears to be the margin is 
really such, it is provided with small teeth, and this would seem to 
relegate it to the Kuropean species; but the presence of teeth is so much 
in doubt that this feature can not be entitled to much consideration. 
The nervation, so far as can be made out, agrees well enough with that 
