ANNIYERSARY ADDRESS OF THE PRESIDENT. Ixvii 



useless synonyms, he proceeds to examine the geological limits now 

 known of the 149 genera, to which belong the 535 species which 

 form the fauna of this formation. He thus iSnds that only 12 of 

 these genera, containing 37 species, belong to the Palaeozoic and Tri- 

 assic formations, and appear for the last time in this zone ; that 47 

 other genera, comprising 71 species, appear here for the first time, 

 and extend in great numbers into the Jurassic series ; that some are 

 peculiar to this horizon, and that the remainder are common both to 

 the overlying and underlying beds. From these lists alone, we find 

 that the greater preponderance of forms connects this zone with the 

 Lias rather than with the Keuper. He then analyzes the different 

 classes with the same general result, except in the case of the Bra- 

 chiopods, which show a greater af&nity to the Keuper than to the 

 Lias. 



Again, looking at the question with regard to species, he finds a 

 far greater number identical with the Lias than with the Keuper, 

 and this with reference to the flora as well as to the fauna. The 

 next question is whether this zone is to be considered as a distinct 

 formation or merely as the lowest member of the Liassic series. 

 There can be no doubt, according to M. Martin, that the number of 

 organic forms which appear for the first time at this horizon is too 

 great and too important not to be considered as characteristic of a 

 distinct epoch; at the same time it is essentially Jurassic in its 

 character, and should therefore be considered as the lowest member 

 of the Jurassic series. The author concludes his paper with a series 

 of propositions involving in a concise manner the arguments above 

 recorded, but which it is hardly necessary to repeat on this occasion. 

 I will merely add that he gives a list of sixteen species common to 

 the Avicula-contorta zone and to the Trias, as well as another list of 

 fifty-seven species common to this zone and the Liassic formation. 



Dr. Benecke, of Heidelberg, in his work on the " Trias and Jura 

 in the Southern Alps," published during the present year at Munich 

 in the ' Geognostisch-pala^ontologische Beitrage,' has taken another 

 view of this question, and endeavours to show, in opposition to the 

 views of Eenevier,Stoppani,and others, that the Ehsetic beds including 

 the Avicula-contorta zone, should be referred to the Trias rather than 

 to the Lias. He denies that the Infralias possesses that peculiar 

 character which justifies its being considered as a distinct form.ation 

 intermediate between the Tiias and Lias. But, independently of this 

 question, the work of Dr. Benecke contains much valuable informa- 

 tion respecting the stratigraphical details of these formations, and 

 the comparison of those of Lombardy with those of Southern 

 Germany. Nor is the palseontological element overlooked. The 

 forms of animal life of the difi'erent strata are carefully compared, 

 and the whole argument is mainlj^ based on sections which he has 

 himself observed in the different districts he describes. 



On a former occasion I gave yon some account of the observations 

 of M. Eenevier on the Infralias or Ehsetic beds in the neighbour- 

 hood of the Lake of Geneva. He has since published an account of 

 the geological formation of the Oldenhorn, a peak which rises to the 



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