STRATIGRAPHICAL GEOLOGY. 489 



The work that has been done by Mojsisovics in the descrip- 

 tion of the Cephalopods, both in the Juvavic Province or 

 Salzkammergut (1873-93) and in the Mediterranean Province 

 (1882), is an achievement of permanent value and general 

 scientific interest. The unusually narrow limits assigned by 

 Mojsisovics to each genus and specific form increases the 

 difficulty of subsequent identification of other specimens, and 

 has been often a cause of complaint. Unlike Thomas 

 Davidson, the founder of the systematic knowledge of Brachio- 

 pods, who left it to posterity to break up his broadly-defined, 

 well-marked genera and species into several, if it were found 

 practicable and desirable (cf. p. 400), Mojsisovics, who has 

 been the chief exponent of Triassic Cephalopods, has founded 

 a system distinguished by the extreme differentiation of its 

 types. But, whatever may be the ultimate verdict of posterity 

 on the system, the work has been so excellently produced that 

 it confers an imperishable boon both on Alpine geology and 

 zoological knowledge. 



There can be no doubt that the keen palseontological sense 

 of Mojsisovics and his subtlety in the differentiation of fossil 

 forms so biassed his mind that, during his surveys in the field, 

 he undervalued the possibility that other causes than facies 

 developments might have produced the local peculiarities in 

 the appearances of the Triassic succession. The tectonic 

 disturbances caused by the repeated crust-movements in 

 Alpine areas did not receive at the hands of Mojsisovics a 

 treatment commensurate with their great significance. And 

 from the year 1866, when the memoir on the geology of the 

 Hallstatt area was published under the combined authorship 

 of Suess and Mojsisovics, the stratigraphical results obtained 

 by Mojsisovics were frequently called in question by other 

 geologists. 



Stur, in 1866, objected to the position assigned by Mojsi- 

 sovics to the salt deposits and Hallstatt limestone. The 

 hydraulic limestones and marls (afterwards the "Zlambach 

 strata " of Mojsisovics) near Aussee covers the salt deposits of 

 that area ; in these limestones Stur had found corals, and 

 close beside them Ammonite species identical with those in 

 the Hallstatt limestone. Again, in certain shales below the 

 salt deposits of Aussee, Stur had found Halobia Lommeli, a 

 typical species of the " Buchenstein " or upper horizon of the 

 Alpine Muschelkalk in South Tyrol, and of the Gossling series 



