Ixiv PROCEEDESrGS OF THE GEOLOGICAI SOCIETY. 



the E-liajtic Beds and White Lias of Somersetshire ; although 

 Mr. B. Dawldns would extend the Ehsetic formation into 

 the grey marls usually considered as belonging to the Keuper, 

 and would place the lower boundary of the E-hsetic forma- 

 tion in the red marls below, considering the alternations of red 

 and grey marls as the passage-bed between the two formations. 

 These two apparently slight discrepancies may, however, be ex- 

 plained by a more gradual passage between the Keuper and the 

 lihsetic beds occurring in England than in the Alps, as evidenced 

 by the existence of these unfossiliferous red and grey marls *. 



The Abbe Stoppani has also published a Memoir on the relative 

 position of the /tvicula-contorta beds in Lombardy. After care- 

 fully considering the recent publications on the subject, he main- 

 tains the conclusion at which he had formerly arrived, that these 

 beds have a greater affinity to tlie Liassic than to the Triassic 

 series. He supports this view both on stratigraphical and palffion- 

 tological grounds, and shows that the Avicula-contorta beds are 

 far more extensively developed in Lombardy, where they have a 

 thickness in some places of from 300 to 400 metres, than elsewhere. 

 After descinbing the fauna which he considers peculiar to these 

 Avicula-conto7'ta beds, he comes to the conclusion that they 

 must be considered as a distinct fonnation between the Trias and 

 the Lias. To this formation he gives the name of Etage Infra- 

 liasien, a name already adopted by many authors, and places it 

 between the Upper Trias or Keuper and the Gryplicea-arcuata beds 

 of the Lias. Like M. Eenevier he divides it into two distinct zones, 

 the upper one of which is the equivalent of the beds of Hettange 

 and of the Dachstein of the Austrian geologists. This Dachstein- 

 formation has already been recognized as intimately connected with 

 the Avicula-contorta beds, and always occurs below those with 

 Gryplicea arcuata and Ammonites BucMandi; and is the Alpine equi- 

 valent of the A.planorhis and A. angulatus zones of the Hettange 

 beds. At the same time the Dachstein is placed rather above the 

 contorta beds. 



The Abbe Stoppani admits, however, that his Infrallas has 

 some points of resemblance with the Upper Trias. It could not 

 indeed be otherwise, when we consider the progressive develop- 

 ment of organic life. But these Triassic characters ai-e very slight 

 and even doubtful, analogies rather than identities, whereas the 

 lowest beds of the Infralias have very decisive characters, and even 

 a large number of species identical with those of the Lias, and 

 these go on increasing as we approach the upper beds with A. 

 planorhis and A. angulatus. Hence he concludes that the Etage 

 Infraliasien is the commencement of the Jura-liassic series. At 

 the same time it must not be confounded with the Lias. Each of 

 these formations has, in connexion with a regular stratification, 

 peculiar petrographical characters, and particularly its own rich 

 fauna, with well-marked features, of which only a very small por- 

 tion passes from one into the other. 



^ Quart. Journ. Geol. Soc. vol. ss. p. 408. 



