E. W. Berry — Late Lower Cretaceous. 49 



species of Equisetum with occasional ferns and possibly 

 a few conifers and, dicotyledons, although the bulk of the 

 species recorded from this locality amounting to a total 

 of thirty and including a Marchantites, an Equisetum, a 

 Sagenopteris, 9 ferns, 9 conifers, 1 monocotyledon and 8 

 dicotyledons, represent fragments of nearby vegetation 

 of a more fertile soil that were washed or blown into the 

 basin of sedimentation. That the equisetum grew in 

 abundance at this place is shown by the profusion of 

 the tuber-bearing underground stems in place in the 

 argillaceous gray sand. This tuber-bearing stratum is 

 immediately overlain by a thin layer of brownish clay 

 containing a variety of leaves and fragments of foliage 

 of different sorts and very large numbers of the aerial 

 stems of the equisetum, and it is a significant fact that 

 these prostrate stems are arranged in a subparallel man- 

 ner as if they had been laid flat by flood conditions and 

 then buried by the fine silt when the flood waters backed 

 up or became slack. This process appears to have been 

 repeated many times, perhaps seasonally, since there are 

 a succession of these alternating tuber-bearing and pros- 

 trate stem-bearing layers. A fragment of the tuber- 

 bearing layer and the character of the aerial stems are 

 shown in the accompanying figures. (Figures 3, 4.) 



Among the other plants found here which serve in a 

 measure to confirm the flood plain character of the 

 deposits, or at least their stream-border character, are 

 the Sagenopteris which appears to have had a habit of 

 growth like that of the existing water-fern Marsilea, the 

 two species of Nelumbites-Lower Cretaceous prototypes 

 of the existing Nelumbo, and the monocotyledonous 

 plant, illogically named Plantaginopsis by Fontaine, 

 w T hich was certainly a semi-aquatic marsh plant with a 

 habit that I- have compared with that of a modern 

 Ericoaulon. 



An interesting dicotyledonous plant common at this 

 locality is Gelastrophyllum latifolium Fontaine. I have 

 for a long time been interested in the angiosperms of 

 the Potomac Group, and the recent discussions of Bailey 

 & Thompson 3 as to whether the vessel-less angiosperms 

 Tetracentron, Trochodendron and Drimys were primitive 

 or specialized by reduction has stimulated a new interest 



3 Thompson, W. P., and Bailey, I. W. ; Mem. N. Y. Bot. Garden, vol. 3, 

 pp. 27-32, pi. 2-4, 1916. Bailey, I. W., and Thompson, W. P., Annals of 

 Botany, vol. 32, pp. 503-512, pi. 16, 1918. 



Am. Jour. Sci.— Fourth Series, Vol. L, No. 295. — July, 1920. 

 4 



