158 Correlation of the Potomac Formations 



Widdringtonites ramosus 

 Cyperacites potomacensis 

 Plantaginopsis marylandica 

 AUsmaphyllum Victor-Masoni 

 Populus potomacensis 

 Populophyllum minutum 

 Populophyllum reniforme 

 NelumMtes virginiensis 

 Nelumbites tenuinervis 

 Sapindopsis variabilis 

 Sapindopsis magnifolia 

 Sapindopsis brevifolia 

 Celastrophyllum denticulatum 

 Celastrophyllum parvifolium 

 Celastrophyllum latifolium 

 Celastrophyllum acutidens 

 Celastrophyllum Brittonianum 

 Celastrophyllum Hunteri 

 Celastrophyllum albwdomus 

 Cissites parvifolius 

 Araliwphyllum crassinerve 

 Aralicephylluin magnifolium 

 Hedercephyllum dentatum 

 Aristolochiwphyllum crassinerve 

 Aristolochimphyllum ? cellulare 

 Menispermites potomacensis 

 Sassafras bilobatum 

 Sassafras parvifolium 

 Sassafras potomacensis 



The total number of forms introduced with the dawn of the Patapsco 

 formation numbers 42 species and includes 5 ferns, 3 of the genera of 

 which are unknown in the preceding floras; 1 Selaginella, which is a 

 decidedly modern type, unique in the fossil state ; 3 cycadophytes, among 

 which the genus DicJiotozamites is new; 5 conifers, among which the 

 genera Pinus and Widdringtonites are unrepresented in the Patuxent- 

 Arundel floras, and Araucarites doubtfully so ; 3 monocotyledons, all mod- 

 ern types; and 25 dicotyledons, which are distributed among 11 genera. 

 All of these genera are unknown in the Patuxent- Arundel flora, and only 

 one, namely, Populus^ which also occurs in the somewhat uncertain 

 Kome horizon, is known in pre-Albian beds anywhere. Moreover, nearly 

 all of these genera are well represented in Upper Cretaceous floras, al- 



