1850.] DARWIN ON BRITISH FOSSIL LEPADID^. 439 



as much truth as that they repose upon Caradoc sandstone. If the 

 Nash hmestone be the equivalent of the Woolhope, then the "Wenlock 

 limestone is wholly omitted, — a singular circumstance, considering the 

 close vicinity of undoubted Wenlock beds at Kinsham, as already ob- 

 served. 



Among the fossils of Nash limestone which have not been hitherto 

 noticed in the Woolhope limestone or its equivalents, or in the beds 

 below it, are — 



Mytilus mytilimeris ? Orbicula striata ?, Sow. 



Pentamerus Knightii, Sow. Forbesii, Davidson. — Sandbanks. 



Orthis orbicularis, Sow. Porites tubulata, Lonsdale. 



rustica, Sow. Cyathophyllum dianthus, Goldf. 



Leptaena euglypha, Balm. Limaria clathrata, Steing. 



lepisma, Sow. fruticosa, Steing. 



transversalis ?, Dalm. Favosites Gotblandica, LamJc. 



On the other hand, the only fossils of the limestone at Nash, Wood- 

 side, and Sandbanks which have not as yet been found in Wenlock 

 limestone or superior strata, are — 



Ortboceras vertebrale ?, Hall. Terebratula Capewellii ?, Davidson. 



Mytilus mytilimeris (Wenlock sbale). Lingula quadrata?, EicJiw. 

 Atrypa_hemisphaerica, Sow. 



The great abundance of the Limaria clathrata, Steing., is a strong 

 fact to overcome in removing the Nash limestone to the bottom of the 

 shale. One inference seems evident : if the Nash limestone is the 

 equivalent of the Woolhope, there is no specific distinction between 

 the organic contents of the two formations of Wenlock and Woolhope. 



June 5, 1850. 



His Grace the Duke of Argyle was elected a Fellow. 



The following communications were read : — 



1. On British Fossil Lepadid^. By C. Darwin, Esq., 

 F.R.S. G.S. &c. 



[This paper was witbdrawn by the author with the permission of the Council.] 



[Abstract.'] 



Mr. Darwin noticed that great confusion exists in the nomenclature 

 of the comparatively few species of Cirrhipeds, hitherto found in a 

 fossil state ; arising both from the easy separation of the several dis- 

 similar valves soon after the death of the animal, and from the im- 

 perfect characters afforded by the valves themselves, which are, as it 

 were, but parts of the crustacean carapace, neither accompanied with, 

 nor distinctly impressed by, any of the soft parts of the animal. He 

 then pointed out such particular valves as were sufficiently distinct, 

 and had sufficiently constant characters to be considered as charac- 



