1845.] BUNBURY ON FOSSIL FERNS. 8? 



18. Aster ophyllites, 



(Undescribed, but said to be found in the " middle coal" near Manchester.) 



19. Artisia ? 



20. Catamites nodosus, 



21. C. duhius? 



I am not aware that any of the three ferns which I have here 

 particularly described, are marked by peculiarities calculated to throw 

 any new light on the questions relating to the climate of the coal 

 period. But the very striking similarity between the coal-plants of 

 North America and those of Europe makes it probable that a simi- 

 lar kind of climate also existed in both countries at that aera ; and 

 whatever conclusions we may arrive at in relation to the carboni- 

 ferous period in the one continent seem equally applicable to the 

 other. Nothing that has yet been ascertained relative to the coal 

 formations of either continent seems at all inconsistent with the sug- 

 gestion of Mr. Lyell* touching the climate of the period in question. 

 This view, which seems to me by far the most probable, is, that the 

 climate was then characterized by excessive moisture, by a mild and 

 steady temperature, and the entire absence of frost, but perhaps not 

 by intense heat. I must admit, indeed, that our materials for the 

 foundation of this theory are perhaps somewhat scanty, being chiefly 

 the general character of luxuriance of the carboniferous vegetation, 

 the great abundance of ferns, and the presence of large-leaved mo- 

 nocotyledonous plants of a tropical or subtropical aspect ; for with 

 regard to the Sigillariae, Stigmarise, Asterophyllites, Calamites, &c., 

 their real affinities are, I think, too doubtful to allow us to found 

 any arguments on them. 



That extreme heat is not necessary to the existence of a very 

 luxuriant and quasi-tropical vegetation, is sufficiently clear from 

 Mr. Darwin's interesting observations on Chiloe and other islands of 

 the southern temperate zonef. Chiloe, situated in the forty-second 

 degree of south latitude, enjoying little summer heat, and subject to 

 perpetual rains and mists, is covered, as he states, with forests of 

 extraordinary density, and the luxuriance of the vegetation is such, 

 that it reminded him of Brazil ; large and elegant ferns, parasitical 

 monocotyledonous plants, and arborescent grasses reaching to the 

 height of thirty or forty feet, are abundant. Indeed, in the south- 

 ern hemispliere generally, owing to the equable climate produced 

 by the great proportional extent of sea, tropical forms both of ve- 

 getable and animal life range much farther from the equator than 

 in our hemisphere. It appears very probable that the climate of the 

 northern temperate zone, during the epoch* in which the coal-mea- 

 sures were formed, may have been similar to that now existing in 

 Chiloe and the adjacent parts of South America. 



Still, considering that the principal coal-fields of England are 

 situated from 13" to 15° farther north than that of Frostburg, of 

 which I have here spoken, the close resemblance of their vegetation 



* Travels in North America, vol. i. p. 148-9. 

 t Darwin's Journal, 2nd edit. p. 242, et seq. 



