MARYLAND GEOLOGICAL SURVEY 221 



Helvet., vol. iii, pi. cxxviii), but only provisional reference is advisable 

 in connection with such a fragment. Knowlton has figured, a leaf from 

 Bridge Creek, Oregon, and referred it provisionally to this species (Bull. 

 U. S. Geol. Survey, No. 204, pi. iii, fig. 5), but the reference is question- 

 able and the comparison is not as satisfactory as in the case of the Mary- 

 land specimen. 



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

 land Creek, Calvert County. 



Collections. — Maryland Geological Survey. 



Genus HICORIA Raf. 

 HlCORIA PSEUDO-GLABRA n. Sp. 



Plate LXXII, Figs. 1, 16, 17. 



Description. — Terminal leaflet broadly obovate in outline, wedge- 

 shaped at the base, finely serrate except near the base, short petioled ; mid- 

 rib thick; secondaries numerous, irregularly disposed, diverging from the 

 midrib at obtuse but varying angles, mostly forking or branching once 

 or twice near their extremities, the branches extending to the serrations ; 

 tertiary nervation fine and close. Lateral leaflets lanceolate (?) in out- 

 line, rounded and inequilateral at the base, entire below, serrate (?) 

 above; secondaries irregularly disposed, sub-parallel, curving upward 

 near the margin, the upper ones branching near their extremities. 



These specimens are so contorted or imperfect that accurate description 

 or comparison is impossible. They have much the appearance of many 

 leaflets of the living H. glabra (Mill) Britton, in which the serrations are 

 often obscure or entirely wanting below. The terminal leaflet may also 

 be compared to Aesculus simulata Knowlton (Bull. U. S. Geol. Survey, 

 No. 204, p. 78, pi. xv, figs. 1, 2) which is apparently a Hicoria rather 

 than an Aesculus. The thick midrib, short petiole, entire, wedge-shaped 

 base, and the irregular angle of divergence of the secondaries together 

 with their branching extremities, are characteristics which are common 



