122 T^NIOPTEEIS. 



Genus T-ffiNIOPTERIS, Brongniart. 

 [Prodrome, 1828, p. 61.] 



Brongniart defines the genus Tmniopteris in his "Histoire" 

 as follows : — 



"Folia simplicia integerrima, nervo medio crasso rigido, ner- 

 vulis perpendicularibus simpKcibus vel basi furcatis. FructLficatio 

 punctiformis."' 



The same author, in his later work,* compares the genus with 

 various recent ferns, and notes the resemblance of some specimens 

 of Tceniopteris vittata, Brong., to Oleandra; a resemblance which 

 Schimper has given expression to in the case of some Tseniopteroid 

 leaves by the adoption of the name Oleandriiium. 



In Sohenk's definition of Tceniopteris, a genus which he places 

 in the Marattiacem, it is described as having " Folia petiolata 

 bipinnata." ^ Saporta, following Brongniart' s original diagnosis, 

 describes the fronds as usually simple, and considerably extends 

 the generic definition* : — 



"Frondes plerumque simplices et tunc petiolo valido instructae 

 (rarius pinnatim compositaB) elongatse toeniatse lanceolatse vel 

 lingulatse nervo marginal! cinctae ; costa media subtus crassa 

 semiteres supra plus minusve gracilis ; nervi secundarii plurimi 

 e costa media sub angulo acuto exeuntes mox subito horizontales 

 numerosissimi simplices vel ssepius a basi pluries furcato-dichotomi 

 usque ad marginem nerviformem recto tramite excurrentes. 

 Fructiflcatio adhuc ignota aut punctiformis, soris punctiformibus 

 totam paginam frondis inferiorem occupantibus." 



He remarks that the exact definition of Tceniopteris constitutes 

 one of the difficulties of fossil botany. The above diagnosis is 

 more comprehensive than the description given by some authors 

 of the same genus ; the genus Oleandridium of Schenk is included 

 by Saporta under the provisional and safer name instituted by 

 Brongniart. Attention is drawn to the Tseniopteroid form which 

 is occasionally assumed by the genus Nilssonia, Brong. ; but there 



' Hist. veg. fo8s. p. 262. 



' Tableau, p. 21. 



" Fl. foss. Grenz. Keup.-Lias, p. 99. 



« Pal. Franp. vol. i. 1873, p. 430. 



