92 .CLADOPHLEBIS. 



venis creberrimis tenuissimis obliquis f urcatis ; rhachi gracili 

 tereti." 



The much more perfect material at present available necessitates 

 an extension and modification of the original diagnosis. 



Frond bipinnate, rachis flat and broad, pinnaB linear lanceolate, 

 alternate to opposite, pinnules falcate, contiguous, attached by the 

 whole of the broad base, acuminate, margin entire or slightly 

 dentate towards the apex. 



Brongniart, in his "Tableau," includes Neuropteris Albertsii, 

 Dunk., among the Wealden plants under the name Cladophlebis 

 Albertsii. Ettingshausen recognized a certain resemblance in 

 Dunker's species to Alethopteris, and adopted that generic name. 

 This change is accepted by Schimper, who remarks on the 

 difficulty of determining the true position of the species from 

 the fragment figured by Dunker. 



In 1871 Schenk * notes the close resemblance of Alethopteris 

 Albertsii, Schimp., to A. Rosserti, Schenk, A. insignis, Lindl., and 

 A. Whitbyensis (Brong.) ; he figures part of a pinna, which, in 

 spite of certain minor differences, is referred to Dunker's species. 

 The same author 2 draws attention to the resemblance between 

 Pecopteris Whitbyemis, Brong., as figured by Trautschold, 3 and 

 Alethopteris Albertsii (Dunk.). 



Heer includes several Greenland specimens from the Atane beds 

 under Pteris (?) Albertsii (Dunk.), but they do not all appear to 

 be quite the same as Cladophlebis Albertsii] some of the figures, 

 however, show a close resemblance to this species. The same 

 genus is adopted by Velenovsky for a fern figured by him as Pteris 

 Albertini (Dunk.), from the Bohemian Cretaceous beds. He draws 

 attention to the complete correspondence between the Bohemian 

 species and the specimens described by Heer from Greenland, but is 

 not decided as to the relationship between Heer's species and the 

 original "Wealden species of Dunker. Some of Yelenovsky 's 

 figures bear a strong resemblance to the English specimens, and 

 might perhaps be included in the synonomy of the species ; this is the 

 case with his fig. 10, also figs. 6, 7, and 8; but figs. 5 and 9 seem to 

 me rather more like the specimens referred by this author to Pteris 



1 Palsoontographica, vol. xix. p. 218. 



2 Ibid. p. 261. 



3 Nouv. Mem. Soc. Nat. Moscou, vol. xiii. 1870, pi. xix. fig. 2. 



