0)1 the Fncctification 0/ EusjDheiiopteris tenella, etc. 129 



III. On the Fructification 0/ Eusphenopteris tenella (Brongn.) 

 and Sphenopteris microcarpa (Lesq.). V>y Kobert 

 KiDSTON. [Plate I.] 



(Read 19th April 1882.) 



1. Eusphenopteris {Bphenopteris) tenella (Brongn.). 

 (PI. I., figs. 1-6.) 



Histoire des Veg^taux fossiles, pi. 49, fig. 1 ; Illustrations of Fo.s.sil Plants, 



pi. xxxix.* 



The barren and fertile fronds of this fern are dissimilar ; 

 and were it not for their occurring in unusually favourable 

 circumstances, it would be impossible to ascertain that these 

 two forms of fronds belong to the same species. I have found 

 no fern associated with Eusphenopteris tenella, with the 

 exception of a single specimen of Sphenopteris delicatula 

 (Sternberg), -f which appears, however, rather to be a small 

 variety of E. tenella than a distinct species, as they are 

 connected by intermediate forms. This circumstance appears 

 to prove conclusively that the fructifying fronds can only 

 belong to E. tenella. 



All the fruiting fronds of this fern with which I have met 

 were collected by myself at Furnace Bank, Sauchie, near 

 Alloa, where it occurs very plentifully, but is limited to a 

 single bed of arenaceous shale lying between the " Eive-Poot 

 Seam " and the Three-Foot Splint Coal. 



Figs. 1 and 2 show two of the most common types of this 

 plant as met with at Sauchie. Brongniart's figure represents 

 only a small portion of a frond ; a much better specimen is 

 shown in the " Illustrations of Fossil Plants ; " but it is there 

 only designated " Sphenopteris sp." 



Eusphenopteris tenella must have attained considerable size, 

 as one of my specimens shows pinnae 7 inches long, given off 

 from an axis only the eighth of an inch thick. Of the barren 

 fronds, some are lax and others much more compact ; we have 

 in the fertile fronds similar distinctions. This is shown in 



* Edited by G. A. Lebour, 1877. 



t "Essai d'un Expose Geognostico-Botanique," Sternberg, pi. 26, fig. 5. 

 VOL. Vll. I 



