MARYLAND GEOLOGICAL SURVEY 22a 
dentate above and entire below, as is the case in these specimens and in 
most of the figures with which they have been compared. Lesquereux 
described a somewhat similar leaf under the name Pterocarya 
americana (Ann. Rept. U.S. Geol. and Geog. Survey Terr., 1873, p. 417; 
Tert. Fl., p. 290, pl. lviii, fig. 3) in relation to which he says: (p. 291) 
“as Pterocarya is an Asiatic genus. .. . it would be more advisable to 
consider the fragment as that of a leaflet of Carya [Hicoria] or of Jug- 
lans.” Knowlton has also described a species under the name Juglans 
cryptata (Bull. U. S. Geol. Survey, No. 204, p. 35, pl. vi, figs. 4, 5) which 
differs but little from the latter, except in size. Under the circumstances 
it does not seem advisable to complicate the synonomy any further by 
introducing the generic name Hicoria, which may more properly be done 
elsewhere. 
Occurrence —SuNDERLAND ForMAtIoN. Near the headwaters of Is- 
land Creek, Calvert County. 
Collections —Maryland Geological Survey. 
Genus POPULUS Linne. 
POPULUS CLARKIANA N. sp. 
Plate LXX, Fig. 6. 
Descriptton—Leaf deltoid in shape, slighily rounded at the center, 
rather abruptly acuminate above, cuneate or sub-cordate below, crenulate- 
dentate except near the base and apex; petiole about 3/10 inch long; ner- 
vation 3-palmate ; lateral primaries and principal secondaries spreading, 
sub-parallel, camptodrome ; from the under sides of the lateral primaries 
and from the outer sides of the marginal loops of the secondaries a series 
of fine nerves and nervilles extend to the crenulations of the margin. 
Named in honor of Professor W. B. Clark, under whose auspices the 
collection was made. There are no described or figured species with 
which this leaf may be satisfactorily compared, but it approaches very 
close to some of the forms of P. deltoides Marsh, especially var. occi- 
dentalis Rydb. 
_ Occurrence—SunpeRtanp Formation. Near the headwaters of 
Island Creek, Calvert County. 
Collections. Maryland Geological Survey. 
