734 Mr. Lonsdale on the Age of the 



Two of the species — Astrea pentagona and Cyathophyllum quadrigeminum, have been noticed 

 in England only in the Devonian series. 



V our— Fenestella antiqua, Favosites pohjmorpha, F. spongites, and Cyathophyllum c<^spitosum, 

 are common to the Devonian and Silurian systems. 



Three— Slrombodes pllcatus, Cyathophyllum dianthus, Astrea ananas, have hitherto been ob- 

 tained in England only in the Silurian formations ; but it is possible that the S. pllcatus may be 

 the Astrea {Cyathophyllum) helianthoides, a Devonian and not a Silurian coral. 



The Anlhophyllum hicostatum has not been noticed in England. 



A summary of these details gives twenty-five fossils, only five of which can 

 be said to be peculiar to the Silurian system, viz. Astrea {Ci/ at hop hi/ Hum) ana- 

 nas, Stromhodes plicatus, Cyathophyllum dianthus, Terehratula Wilsoni, and 

 Spirifera lineata? but the Terebratula is Tprohnh\y not an accurate identifi- 

 cation ; and the Spirifera is given by M. Dumont with a doubt*. 



The lists which I have ventured to analyse are small, but the evidence they 

 afford is valuable, consisting not in the absence of characteristic suites of pe- 

 culiarly Silurian fossils, but in the presence of Devonian and carboniferous spe- 

 cies, which have not been detected in any of the Silurian beds. If it should 

 be objected that an attempt has been made to establish a case by lists and 

 not by specimens, it may be replied that the lists bear all the internal 

 evidence of having been carefully prepared. They contain no species which 

 may be considered as apocryphal, and they possess a unity of character with 

 lists from other localities in the same country, drawn up by independent ob- 

 servers. It should also be remembered that M. Dumont's judgement while 

 preparing the lists could not have been biased by any theory ; for he had 

 none to advocate. His sole object in examining the country around Liege 

 was to work out a difficult district, and to prove the order of superposition of 

 strata strangely contorted and inverted. This task it must be universally 

 allowed, he accomplished in a manner deserving of all praise. At that time, 

 he thought not of identifying his systems with those of England ; and if it 

 should be proved that the comparison is erroneous, the failure must be solely 

 ascribed to not taking into his consideration the only means by which distant 

 countries can be identified, a right application of organic remains. There 

 can be no doubt also, that M. Dumont was guided, to a great extent, in his 

 classification of 1838, by having determined in 1836, that the systeme 

 calcareux inferieur was the equivalent of the Eifel limestone. (See Bull. 

 Soc. Geol. de France, t. viii. p. 77. Dec. 1836.) 



I am called upon to offer a few remarks on one other case. 

 During the Reunion extraordinaire of the Geological Society of France, 

 at Porrentruy, in September 1838, M. de Verneuil read a notice on the an- 



* The fossils from the Systeme quartzo-schisteux inferieur having been identified on insufficient 

 evidence, any notice of them has been considered unnecessary. 



