CVl PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



new subdivision of the Permian series. After quoting the Abbe 

 Landriot, as beheving them to constitute a passage from the zeehstein 

 into the coal-measures, M. Delahaye remarks, that in the basin of 

 Autun the upper beds of the schists contain an abundance of Fsa- 

 rolithes identical with those of the new red sandstone {gres rouge)^ 

 and that in parts of the basin, at Ygornay, at Chambois, and other 

 places, and reposing conformably on the schists, there is a grey rock 

 sometimes containing bituminous veins, at others presenting a dirty 

 olive-coloured aspect from a more general dissemination of bituminous 

 matter, offering the normal characters of zeehstein, and upon analysis 

 affording the carbonates of lime and magnesia. He also calls atten- 

 tion to the opinion of M. Agassiz, that the fish-scales found in all the 

 upper beds of the basin of Autun and the fossil fish of the lower 

 parts of the schists of Muse bear the greatest resemblance to the re- 

 mains of Palseoniscus discovered by M. von Dechen in the limestones 

 subordinate to the new red sandstone {gres rouge) of Bohemia. M. 

 Delahaye refers the fish-scales above noticed to the Palceoniscus 

 magnus, thought by M. Agassiz to be exclusively contained in the 

 zeehstein of Mansfeld. A general view is taken of the fossil plants 

 found in the environs of Autun. 



At a subsequent meeting of the Society, while MM. Virlet and 

 Boubee supported the \'iew that the bituminous schist of Autun was 

 independent of the coal-measures, M. Elie de Beaumont combated 

 this opinion, stating that analogous bituminous schists were fomid in 

 many other of the coal basins of France and foreign countries. 



Mr. Davidson communicated a detailed memoir on the Brachiopods 

 of the Upper Silurian system of England, the result of his labours in 

 the districts where these rocks are found and among local collections. 

 He considers it as now recognized that many species have lived 

 through the times of deposit of several stages of the Silurian system, 

 and have been even perpetuated beyond it. He is also of opinion 

 that the divisions proposed by Sir Roderick Murchison are charac- 

 terized by certain species more abundant in or proper to them, so 

 that these divisions may be usefully preserved, without at the same 

 time attaching more importance to them than is their due. 



Respecting generic divisions, Mr. Davidson observes as probable, 

 that as we advance and lacunes are filled up, distinctions vdll become 

 more and more arbitrary. " Thus," he continues, " confining our- 

 selves to the Brachiopods, do we not daily find the great differences 

 disappearing which once served to characterise the genera Productus, 

 Chonetes, Orthis, Leptcena, Spiinfer, Terebratula, &c. ? Do we not 

 find these genera more and more approximating to each other by a 

 multitude of intermediary species, some possessing the external forms 

 of one genus with certain internal characters of another, so that 

 there is much difficulty in assigning them their true place ? We may 

 cite as examples the Orthis hiloha and the Orthis biforata or lynxy 

 which possess the internal characters of an Orthis and the external 

 forms of a Spirifer. The genus Aulosteges of M. Helmersen comes 

 between the Productus and the Orthis^ After observing that a 

 great number of examples might be adduced of the little value to be 



