RAPPAHANXOCK RIVER SECTIONS. 



73 



RAPPAHANNOCK RIVER SECTIONS. 



Exposures of the Patuxent are frequent in the vicinity of Fredericks- 

 burg, althougli they are for the most part covered with Eocene or surficial 

 deposits. From Falmouth, about 1 mile above Fredericksburg, occasional 

 exposures along the river show upwards of 30 feet of the arkosic gray 

 sands of the Patuxent formation. A somewhat argillaceous lens of these 

 materials near the steamboat landing at Fredericksburg yielded the large 

 number of fossil plants for which this locality is famous. These have fur- 

 nished the only adequate materials for a study of the Patuxent flora. The 

 following are the more important forms identified from this locality : 



Schenk 

 (Dunk.) 



Acrostichopteris adiantifolia (Font.) 



Berry 

 Acrostichopteris parvifolia Font. 

 Acrostichopteris pluripartita ( Font. ) 



Berry 

 Arthrotaxopsis grandis Font. 

 Carpolitliiis agglonicralus Font. 

 CarpolitJius conjugatus Font. 

 Carpolithns curviatus Font. 

 Carpolithus fascicitlatus Font. 

 Cephalotaxopsis brevifolia Font. 

 Cephalotaxopsis magnifolia Font. 

 Cladophlebis Albertsii (Dunk.) Brongn. 

 Cladophlehis distans Font. 

 Cladophlebis constricia Font. 

 Cladophlebis virgin iciisi^ Ff)nt. 

 Cladophlebis parva Font. 

 Cladophlebis Ungeri (Dunk.) Ward 

 Cladophlebis Broioniana (Dunk.) Ward 

 Ctenis imbricata Font. 

 Ctenophyllum latifolii(m Font. 

 Ctenopteris insigvis Font. 

 Ctenopteris longifolia Font. 

 Cycadeospermum ellipticum Font. 

 Dryopteris cystopteroides Font. 

 Dryopteris Dunkeri Font. 

 Equisctum Lyelli Mant. 

 Ficophyllum serratum Font. 

 Ficophyllum oblongifolium Font. 

 Frenelopsis ramosissima Font. 

 Leptostrobus longifolius Font. 

 Nageiopsis longifolia Font. 

 Nageiopsis angvstifoUa Font. 

 Nageiopsis zamioidcs Font. 

 Nilsonin dcnsinerve (Font.) Berry 



Southeast of the town no Potomac materials are seen along the river for 

 about 2 miles. Below this point, for a distance of about 6 miles or to 

 about half a mile below the mouth of the Massaponax, the banks show 



Onycliiopsis goepperti (Selienck) Berry 

 Onychiopsis psilotoides ( Stokes & Webb ) 



Ward 

 I'odosamites distantinervis Font. 

 Proteaephyllum ovatum Font. 

 Proteaephyllum reniforme Font. 

 I'ogrrsia angustifolia Font. 

 Rogersia longifolia Font. 

 Ruffordia Goepperti (Dunk.) Seward 

 ^ageiioptcris virginicnsis Font. 

 ^clcropteiis elliptica Font. 

 Sequoia amhigua Heer 

 Sequoia Reichenbachi (Gein) Heer 

 Sphenolcpis Kiirriuna (Dunk. 

 Sphenolepis Sternbergiana 



Schenk 

 Taeniopteris auriculata (Font.) Berry 

 Tacnioplcris nervosa (Font.) Berry 

 Thinnfeldia rotiDidiloba Font. 

 Thyrsopteris dentata Font.' 

 Thyrsopleris crenala Font. 

 Thyrsopteris divaricata Font. 

 Thyrsopinis crassinervis Font. 

 Thyrsopteris angustiloba Font. 

 Thyrsopteris heteroloba Font. 

 Thyrsopteris heteromorpha Font. 

 Thyrsopteris heterophylla Font. 

 Thyrsopteris nana. Font. 

 Zamifes crassinervis Font. 

 Zamitcs tenvinervis Font. 

 Zamiopsis insignis Font. 

 Zamiopsis laciniate Font. 

 Zamiopsis longipennis Font. 

 Zamiopsis petiolata Font. 



'These species of Thyrsopteris have not yet been restudied. 



