Isvi PEOCEEDINGS OP THE GEOLOGICAL SOCIETr. 



equally connected with tlie Keuper and tlie Lias as a true natural 

 transition-formation. In England the bone-bed is petrographi-" 

 caliy as much connected with the Keuper as with the Lias. The 

 bone-bed arkose of Central France is equally referable to both. 

 In Eastern France and Germany, the hard yellow bone-bed sand- 

 stone is conformable to the similar formations of the Keuper, and 

 quite unconformable to the limestone-beds of the Lower Lias. In 

 the Alps it appears to be equally conformable to both. Strati- 

 graphically, the " contorta-heds^' are more conformable to the 

 Keuper than to the Lias ; and he comes to this conclusion, that 

 although no universal unconformability to the Lias can be found, 

 yet there is nowhere a want of conformability to the Keuper. 



The author concludes with a list of the characteristic fossils of 

 the "conforta-heds,''^ and then points out where these or representa- 

 tire forms occur in the older or younger formations, with this result 

 —that of 162 species in the " contorta-heds,'' 90 occur in the older 

 and 72 in the newer formations, and 12 Occur in all. It has been 

 well said that anything may be proved by numbers, and the author 

 admits that the representative species are not all of equal typical 

 importance. He adds to the name of each species the number of 

 D'Orbigny's Etage in which it is found, to show that the analogues, 

 of the Avicula-contorta zone in the older beds are placed much 

 nearer to it than those which occur in the newer or overlying beds. 

 And finally, relying much on the opinions of Alberti and Quenstedt, 

 he concludes that the Avicula-contorta zone should be referred to 

 the Keuper rather than to the Lias. A list of the authors wha 

 have adopted these difierent views is also given, as well as a list of 

 458 species of organic remains of all classes from the " contorta- 

 zone." 



In connexion with this subject, I must notice a paper read by 

 Mr. Bristow at the Meeting of the British Association at Bath.- 

 Mr. Bristow had been instructed, on the part of the Geological 

 Survey of Great Britain, to examine those beds between the New 

 Eed and the Lower Liassic strata, to which the term Ehsetic 

 had been applied. Having visited several localities in the neigh- 

 bourhood of Bristol and elseAvhere, from Cheltenham to Penarth, 

 near Cardiff, Mr. Bristow was enabled to map these beds in the 

 neighborhood of Bristol, Saltford, Keynsham, and Uphill, on 

 the borders of the Lias to the North and South of Bristol, and at 

 Penarth and other places in the district. He described them as 

 everywhere underlying the true Liassic strata, but owing to their 

 comparative thinness they are seldom fairly exposed. They 

 consist' chiefly of a central mass of black shales, resting on and- 

 passing into the underlying red and variegated Keuper marls,, 

 whilst beds of marl and marly or argillaceous limestone, consti- 

 tuting their uppermost division, form the base of the Lias, cha- 

 racterized by the presence of Ammonites pJanorbis and the great 

 abundance of Ostrea liassica. 



■ The upper limit of these Ehastic beds is well marked by the 

 "White Lias," which Mr> Bristow considers its uppermost mem- 



