36 Later Extinct Floras of ATorth. AmerkU, 



The notes on some of the species contained in the collection 

 made by Dr. Hayden, S>/i(ot\t Litngsdorfli, SabaJ Camp- 

 I,,//;, Onoclea sensibilis, &c, have a bearing on the general 

 questions to which reference lias been made in the preceding 



pag< B, I nit the occurrence of an <hu><-l<a among these Miocene 

 plants, and a species which I cannot distinguish from the living 

 one, Beema to me a fact of so much importance as to require 

 some additional comments. 



The fern frond found by the Dnke of Argyle, in the leaf beds 

 of tin- [eland of Mull, and figured by Prof. E. Forbes, in the 

 Journal of the Geological Society of London, vol. vii. (1851), 

 p. L03, pi. ii. figs. 2a, 2b, and named by him Filicites (?) He- 

 bridicus, is unquestionably identical with this. The specimen 

 from which the figures to which 1 have referred were taken. 

 Beems to have puzzled Prof. Forbes somewhat, for he even 

 doubted if it were a fern ; and Prof. Ileer, in his reference to 

 the fossil plants of the Island of Mull (Flor. Tert. Helvet. 

 \ul. Hi. p. :;| 1 1, says: "The most remarkable species is Fili- 

 <-,'/., / Hebrjdious, a fern, which by its nervation differs greatly 

 from those of the continent." All these facts give this fossil 

 speoial interest, for in addition to its relation to its living rep- 

 titative8, of which we cannot but consider it the progenitor, 

 ii adds another to the li.-t of plants common to the Miocene 



strata of Europe and America. ( >f the-e. either representative 

 or identical species, the number is now so great thai they 

 plainly indicate a land connection between the continents at 

 thai period; and Bince many genera, and this, with probably 

 some other species at tint time common to the old and New 

 Worlds, have disappeared from Europe, while they continue to 

 flourish here, it would seem to follow thai these were Ameri- 

 can 'ype- which ha<l colonized Europe by migration, and that 

 when their connection with the mother country was severed, 

 they were overpowered and exterminated by the present flora 

 of Europe, which, as Prof. Graj has Bhown, is mainly of V 

 A-';/ ■ origin. 



