MARYLAND GEOLOGICAL SURVEY 223 



dentate above and entire below, as is the case in these specimens and in 

 mosi of the figures with which they have been compared. Lesquereux 

 described a somewhat similar leaf under the name Pterocarya 

 americana (Ann. Eept. U. S. Geol. and Geog. Survey Terr., 3 873, p. 417; 

 Tert. Fl., p. 290, pi. 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, pi. 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. 



Description. — Leaf deltoid in shape, slightly 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. occl- 

 dentalis Eyclb. 



Occurrence. — Sunderland Formation. Near the headwaters of 

 Island Creek, Calvert County. 



Collections. — Maryland Geological Survey. 



