﻿186 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 12, 



hand, has given the name of Glossopteris Dunnii to the broader 

 form, considering it as a distinct species. 



It has often been remarked that the extinct plants and animals 

 found in a fossil state are more dissimilar to those now existing, in 

 proportion as the formation in which they occur is more ancient ; 

 that those in the oldest rocks are most unlike our present creation, 

 and that in the secondary and tertiary periods they gradually ap- 

 proximate to it more and more. But however true this may be as a 

 general rule, the Ferns, I think, form an exception to it. The Ferns 

 of the Oolite can hardly be said, on the whole, to resemble the recent 

 kinds more closely than do those of the Carboniferous period. The 

 Alethopteris lonchitica, and its allies, found in the old Coal-formation, 

 are so exceedingly similar to existing Ferns, that some care is re- 

 quired to distinguish them even specifically. The Pecopterides of 

 the Coal-measures are not, generally speaking, less similar to recent 

 Ferns than those of the Oolite. And our Sagenopteris Phillipsii, 

 on the other hand, although there can be no doubt that it is a Fern, 

 appears as different from all existing forms as any of those in the 

 Coal-formation. Its venation indeed is not unlike that of some recent 

 species, — of Hemionitis, for example ; and the digitate form, though 

 very rare, is not quite without recent analogy ; but in no living Fern, 

 at present known, is there the combination of the digitate frond with 

 the reticulated venation. 



4. Pecopteris cespitosa, Phillips, Geol. Yorks. pi. 8. f. 10. 



This remarkable plant, although there is a characteristic figure of 

 it in Mr. Phillips's work, is entirely omitted by Brongniart (even in 

 his latest list of fossil plants of the Oolite), by Goeppert, and by 

 Unger. I mention it here, chiefly for the purpose of expressing a 

 doubt respecting its true structure, which I think worthy of atten- 

 tion. Prof. Phillips gave it the name of ccespitosa, under the 

 impression (as he informs me) that the specimen which he figured 

 consisted of a cluster of pinnated fronds springing from a tufted 

 rhizome ; and this appearance is well expressed in his plate. But 

 the specimen which I have examined in Dr. Murray's collection gives 

 quite a different idea of the structure of the plant : it has all the ap- 

 pearance of a compound frond, with five or six pinnae radiating in a 

 fingered form from the top of a broad stalk, and spreading out all in 

 one plane. Another specimen, which Mr. Phillips showed me in his 

 own collection (and which he obtained after the publication of his 

 work), presents a similar appearance. None of these, unfortunately, 

 are sufficiently well-preserved to remove all doubt as to the real form 

 of the plant ; and it remains to be decided by the discovery of more 

 perfect specimens, whether the frond of this Pecopteris was merely 

 once pinnated, or digitate, with pinnated divisions. I think this a 

 point worth the attention of those who may have an opportunity of 

 making further researches in the Scarborough plant-beds. In either 

 case this Fern appears to be a very distinct species from any other 

 yet known in the same formation. If it had pinnated fronds spring- 



