V] 



RHACOPTERIS AND SPHENOPTERIDIUM 



61 



Rhacopteris, Schimper, 1872 (Fig. 33). Fronds pinnate or 

 dichotomously branched. Pinnules large, unsymmetrically 

 wedge-shaped, rhoniboidal, typieally entire or more or less 

 deeply lobed or divided longitudinally, Avith a radiating un- 

 symmetrical nervation. Higher part of the frond sometimes 

 fertile, si^orangia tnfted, small, exannulate, globular. 



This genus is very rare in the Devonian, though it appears 

 to occiu- on that horizon in German3\ It is more characteristic 

 of the Lower Carboniferous. 



Distribution. Upper Devonian to Middle Coal Measures. 



Fig. 83. RJtacopleris fiircillata, 

 (Ludvv.), from the Upper Devo- 

 nian of Germany. (About J nat. 

 size.) After Potonic (1901). 



Fig. 34o Sphenopteridiinn rigi- 

 dum, (Luaw.), from the Upper 

 Devonian of Enaland and Ger- 

 many. (About I nut. size.) 

 After Potonie (.1901). 



Sphenopteridium^, Schimper, 1874 (Figs. 34, 35). An indefin- 

 able generic name applied to a particular type of Spheno2:)terid 

 frond in which the pinnules are highly divided into very narrow 



1 This term is to be preferred to Rhodea, Presl, 1838, since that term is 

 preoccupied for Angiosperms {Rhodea, Endlicher, 1837; Rvhdea, Roth, 

 1821). 



