Maryland Geological Survey 425 



are allied with genera which in the modern flora are confined to tropical 

 areas where the humidity is high and the rainfall heavy. 



It is possible that these peculiar features in the Cretaceous species of 

 Frenelopsis were inlierited from Triassic ancestors which acquired them 

 during these portions of the Triassic when the climate was extremely 

 arid, as we know it was from physical as well as paleontological criteria. 



This species, which is exceedingly abundant in the oldest Potomac at 

 Fredericksburg, Virginia, occurs sparingly at higher horizons both in 

 that State and in Maryland. It may be distinguished from the following 

 species and from Frenelopsis Holieneggeri by the short branches, their 

 crowded habit, and the short internodes. The latter species is described 

 as having the leaves in pairs and opposite while in F. ramosissima they 

 are in whorls of three, but this can have but little significance since in 

 the living forms the leaves normally in threes occur singly, in pairs, or 

 in fours. The following species often shows but a single leaf at the 

 nodes while F. leptodada Sap. has the leaves either opposite or in fours. 



Perhaps the most nearly related species is Frenelopsis occidentalis 

 Heer of the Barremian, Albian and Cenomanian of Portugal, but this is 

 abundantly distinct, in fact the majority of species of this genus taken 

 as a whole constitute a group of forms closely related to the type species 

 with which some of them may even be identical, while F. ramosissima 

 stands by itself as a markedly distinct type. 



Occurrence. — Patuxent Formation. Fredericksburg, Virginia. 

 Patapsco Formation. Federal Hill (Baltimore), Maryland; Chinkapin 

 Hollow, Hell Hole (?), Virginia. 



Collections. — U. S. National Museum, Johns Hopkins University. 



Frenelopsis parceramosa Fontaine 

 Plate LXX, Figs. 1-5 



Frenelopsis parceramosa Fontaine, 1890, Mon. U. S. Geol. Survey, vol. xv, 

 1889, p. 218, pi. cxi, figs. 1-5; pi. cxii, figs. 1-5; pi. clxviil, fig. 1. 



Frenelopsis parceramosa Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., 

 vol. xlviii, 1905, pp. 544, 584. 



