ANNIVBRSAKY ADDRESS OF THE PBESIDEHT. .' Ixxl 



in the Anglo-Parisian basin. It is the extreme northern point of 

 a new (the Aquitanian) basin. Here argillaceous beds predomi- 

 nate, and the general facies of the fauna approaches that of Cap 

 de la Heve. But the calcareous element is not altogether wanting, 

 the upper beds consisting of a marly limestone and clays, and the 

 lower of calcareous marls ; and we find this remarkable fact, 

 that in proportion as the clays predominate, the fauna, rich in 

 Lamellibranchiata, resembles that of the north. When the lime^ 

 stones prevail, as in the upper and lower zone, the (xasteropods 

 and Cephalopoda resume the preponderance. Thus it is impossible 

 to compare exactly the faunas of the different subdivisions, since 

 they must be considered as accidental assemblages peculiar to the 

 localities, and the result of the contest between the limestone and 

 the clay formations. But looking at the whole from a higher point 

 of view, we find towards the north the Ostrece and similar forms 

 selecting those localities where argillaceous deposits were being 

 formed, whilst towards the south-east the higher forms of MoUusks 

 sought out those spots where the sea was impregnated with cal- 

 careous matter. The author concludes by remarking that, without 

 attaching too much importance to the theory of migration, we 

 might imagine these animals moving from place to place, accord- 

 ing as local influences modified more or less the nature of the sea 

 which they inhabited ; thus assembling, as it were, round those 

 points which were most favourable to their existence. At all events, 

 the close connexion of the Cephalopods and Grasteropods, parti- 

 cularly the Nerintese, with the calcareous deposits, is a very inter- 

 esting fact, which establishes the great and unquestionable differ- 

 ence between the faunas of the northern and of the south-eastern 

 portioDs of the basin. 



The second part of the work contains a list of 132 species of 

 organic remains found in the Kimmeridge beds of Cap de la Heve ; 

 and in the third part is a detailed description of the new or doubt- 

 ful species, with eighteen plates of figured illustrations. 



Prof Credner has contributed to our knowledge of the Geology 

 of Northern Germany, by the publication of a valuable work "On 

 the subdivision of the tipper Jura formation and the Wealden; 

 formation in the North-West of Germany." An inquiry into the, 

 extent of the Coal-deposits in the North "German Wealden forma- 

 tion, and into the occurrence of salt-springs in the underlying 

 beds, first led him to construct several sections of the strata which 

 exist in that district between the Brown Jura and the Chalk. 

 These beds belong in the north-west of Germany to two princi- 

 pal divisions : — 1st, marine deposits of the Upper Jura formation ; 

 and 2nd, the fresh or brackish water deposits of the Wealden 

 formation, which alternate with each other in a remarkable 

 manner. They extend from the north-western flank of the Hartz. 

 Mountains to the frontiers of Holland, where they disappear 

 under the thick diluvial covering. They appear to have been 

 formed in several distinct basins, the deposits of wliich show a 

 great amount of diversity. 



