538 Palaeontologie. 



)iopsis marylandica Fout, Alismaphyllum Victor- Masoni (Ward; Ber- 

 ry, gen. nov., Popithis potomacensis Ward, Populophyllum minutum 

 Ward, P. reniforme Fout, Nelumbites virginiensis (Fout.) Bery, gen. 

 nov., TV. tenuinervis (Fout.) Berr}^ Menispermites potomacensis sp. 

 nov., Sapindopsis variabilis Fout, S. magnifolia Fout, S. brevifolia Fout, 

 CelastropJiylhtm denticulatum Fout, C. parvifolinm (Fout.) Berr3 T , C. 

 latifolium Fout, C. acutidens Fout, C. Brittonianutn Hocenk, C. Hun- 

 ten Ward, C. albaedomiis Ward, Cissites parvifolias (Fout.) Berry, 

 Sassafras bilobatum Fout, 5". parvifolinm Fout, 5. potomacensis sp. 

 nov., Araliaephyllum crassinerve (Fout.) Berry, A. magnifolium Fout. 

 Incertae sedis: Heder aephyllum dentatum (Fout.) Berry, 

 Ficophyllum serratum Fout, F. oblongifolinm (Fout.) Berr} 7 , Proteae- 

 phyllum reniforme Fout, P. ovatnm Fout, Rogersia longifolia Fout, 

 R. angiistifolia Fout, R. angastifolia parva Fout, Aristolochiaephyllinn 

 crassinerve Fout, A. ? cellulare Ward. 



The Patuxent flora embracing about 100 speeies contains nurae- 

 rous well known Neocomian types nearly 40 of which have not been 

 found in the Arundel or Patapsco floras. 



The Arundel flora numbers 33 speeies of which only four are 

 peculiar, the majority of the forms being common to the Patuxent. 

 The Patapsco formation is separated from the older Cretaceous 

 by a considerable erosion interval during which sixty one speeies 

 of the Patuxent- Arundel flora became extinet. The Patapsco flora, 

 embracing about 100 speeies, is marked by the introduetion of 42 

 speeies which include 5 ferns, one Selagineüa , 3 cycadophytes among 

 which the genera Ctenopsis and Dichotosamites arenew, 5 conifers, 

 3 monocotyledones and 25 dicotyledones. All of the last type of 

 plants are of genera unknown in the Patuxent-Arundel flora and 

 only one genus, namely Populus, which oecurs at the somewhat 

 uncertain Korne (Greenland) horizon, is known in pre-Albian 

 beds anywhere. 



The following may be mentioned as among the more interes- 

 ting paleobotanical results of the present stud}^. The definite refe- 

 rence of the supposed ginkgoalian genus Baieropsis to the genus 

 Schisaeopsis of the family Schisaeaceae and to the genus Acrosticho- 

 pteris, the latter also probably referable to the same family. 



The presence in the Patapsco formation of a new genus of ferns, 

 Knowltonella , which appears to be a simple type of the family 

 Matoniaceae. 



The elimination of large numbers of supposed speeies of Clado- 

 phlebis, Pecopteris, Thyrsopteris and Sphenopteris, which are divided 

 between the genera Cladophlebis and Onychiopsis, and the reference 

 of the former to the family Polypodiaceae. 



The genus Sagenopteris is referred to the Hydropteraceae and 

 Taeuiopteris and Tempskya are somewhat doubtfully referred to the 

 Marattiaceae. The latter genus, common in the European Cretaceous, 

 has not heretofore been recorded from North America. 



Among the cycadophyta the genera Ctenopsis and Dichotozamites 

 are described as new and a large and typical speeies of Nilsonia 

 is recognized for the first time, while the number of speeies in 

 Zamia, Zamiopsis, and Podosamites are greatly reduced. 



The five speeies formerly referred to Cephalotaxopsis are reduced 

 to two. The fourteen supposed speeies of Nageiopsis are reduced to 

 three, and a similar reduetion in speeies through the correlation of 

 separated fragments oecurs in the genera BrachyphyUum, Pinus, 

 Abietites, Laricopsis, Sphenolepis, Arthrotaxopsis, Sequoia, etc. 



