224 SYSTEMATIC PALEONTOLOGY 



POPULUS LATIOR Al. Br. ? 



Plate LXX, Fig. 7. 



Populus latior Al. Br., 1837, in Buckland, Geology, vol. i, p 512. 



Description. — Although fragmentary and imperfect this specimen 

 shows characters sufficient to identify it, at least provisionally, with the 

 above species and probably with the variety rotundata as figured by Heer 

 (Fl. Tert. Helvet., vol. ii, pi. lvi, figs. 4-7). It may also be compared 

 with P. lindgreni Knowlton (18th Ann. Kept. IT. S. Geol. Survey, pt. 

 3, p. 725, pi. c, fig. 3 ; Bull. IT. S. Geol. Survey, No. 204, p. 29, pi. ii, 

 fig. 1) and it is evidently closely related to the living P. deltoides Marsh, 

 all of which differ from each other less than the leaves of the latter, on a 

 single tree, often differ between themselves. 



Occurrence. — Sunderland Formation. Near the headwaters of Is- 

 land Creek, Calvert County. 



Collections. — Maryland Geological Survey. 



Populus pseudo-tremuloides n. sp. 

 Plate LXX, Fig. 5. 



Description. — Leaf orbicular or transversely elliptical in shape, taper- 

 ing abruptly and about equally to the somewhat decurrent base and acumi- 

 nate apex, about 1 1/10 inch in length and width; margin entire; petiole 

 \ inch in length; nervation 3-palmate, camptodrome; lateral primaries 

 arising from very near the base of the leaf at an angle of about 45 de- 

 grees with the midrib and curving gently upward, each with three secon- 

 daries on the lower side curving toward the margin; median secondaries 

 fine, about two on each side of the midrib, extending upward at acute 

 angles and curving at their extremities. This leaf is hardly to be dis- 

 tinguished from many entire-margined forms of the living P. tremuloides 

 Michx. and is similar to P. decipiens Lesq. (Tert. FL, p. 179, pi. xxiii, 

 figs. 7-11), although in this species the lateral primaries are more upright. 



Occurrence. — Sunderland Formation. Near the headwaters of Is- 

 land Creek, Calvert County. 



Collections. — Maryland Geological Survey. 



