ONYCHIOPSIS. 47 



become OnycJiiopsis Mantelli \ this change being a necessary con- 

 sequence of the discovery by Yokoyama of fertile pinnae in 

 Onychiopsis elongata (Geyl.), a Japanese plant very closely allied to 

 the Western 0. Mantelli. Previous to Yokoyama's important paper 

 in the Journal of the Imperial University of Japan, in which the 

 generic name Onychiopsis is first proposed, a very similar fern 

 with fertile segments had been figured by Velenovsky, from the 

 Cenomanian beds of Bohemia, under the name Thyrsopteris 

 capsulifera; 1 these species, as Nathorst remarks, must also pass 

 into the newer genus. These discoveries of such characteristic 

 Onychium-VikQ fructifications enable us to include under Yoko- 

 yama's genus a group of plants previously referred to Sphenopteris, 

 Thyrsopteris, Dicksonia, etc., and, at the same time, afford valuable 

 evidence as to the existence of an Onychium type of fern in Upper 

 Hesozoic times in England, North Germany, Bohemia, Japan, and 

 several other districts. 



Finally, the same species has recently been recorded by 

 Engelhardt from the Cenomanian of Mederscho'na ; unfortunately 

 no figures accompany the description. 



As Zeiller 2 has pointed out, this discovery of a Wealden fern 

 in rocks referred to a higher horizon in the Cretaceous system is of 

 considerable interest. 



In the diagnosis of the species reference has been made to the 

 characters of the fertile pinna3, which will be more fully dealt with 

 in the descriptions of such examples as occur in the collections 

 (V. 1069, V. 2151, V. 2159, V. 2159a). Having found the fertile 

 specimens of this well-known species I endeavoured to determine 

 what genus of recent ferns might best be taken as the nearest 

 living representative ; the two genera Onychium, Kaulf., and 

 Cryptogramme, R. Br., appeared to come nearest to the fossil 

 forms, but of the two the former showed a more intimate re- 

 semblance. 



No distinct traces of sporangia have been detected in the fossil 

 species, and the comparison between Onychium and Onychiopsis 

 Mantelli is, therefore, based on the general habit of the fertile 

 fronds and the form of the sporangiferous pinnules. Whilst still in 

 doubt as to how far the evidence at command warranted a change 



1 Velenovsky, loc. cit. pi. i. figs 6-12. 



2 Ann. geol. vol. viii. 1892-93, p. 893. 



