FAUNA OF THE PROVINCE OF THE MEDITERRANEAN. Ill 



confusion into any stratigraphical or genetic classification. We have not yet 

 been able to find any such case. 1 



Examples of mixed faunas such as have been quoted above are not so exten- 

 sively mixed as has been claimed. The Hierlatz and Adneth limestones are, 

 for example, mixtures only of the faunas of the beds above the Angulatus bed ; 

 the examples given of so-called psiloceran forms as occurring in them are due 

 to mistakes in identification, since these forms are species or young of species of 

 Arnioceras or Agassiceras, and the species cited as belonging to the Middle and 

 Upper Lias are either radical forms or else morphological equivalents, like all 

 the so-called anachronic forms which we have yet studied. A paper by W. B. 

 Clarke 2 is very instructive in this connection, since he found in the Rhsetic a true 

 Arcestes, showing conclusively how favorable this region must have been for the 

 preservation of ancient forms. He also was able to make out and describe the 

 Planorbis and Angulatus horizons, with a full list of species already described by 

 Wahner and others, and, above this, the Hierlatz horizon. 



The facts appear also to accord perfectly with the theory of autochthonous 

 faunas. If the Northeastern Alps were the seat of origin for the major portion of 

 the radical forms of Arietidaa, we should naturally expect to find in this province 

 the geological and zoological relations which are shown in Table VI. ; namely, 

 a clear definition of the lower formations and faunas throughout the Planorbis 

 and Angulatus horizons, and an extraordinary number of radical species and 

 their immediate allies, these also having in the sutures a more ancient or triassic 

 aspect than in Central Europe. An analdainic fauna made up of modified forms 

 arising by migration from other faunas would necessarily be shown either in the 

 admixture of forms above these horizons in case the sediments were similar and 

 continuous, or else in the non-appearance of new radical or progressive forms if 

 the sediments were more varied and more distinctly separable, as in England 

 and in the basin of the Rhone. 



While the Mediterranean province was an analdainic fauna so far as the Arie- 

 tidaa were concerned during the deposition of the upper beds of the Lower Lias, 

 subsequent to the deposition of the Angulatus beds, this was by no means the 

 case with other groups, such as the Lytoceratidas. On the contrary, as has been 

 already announced by Neumayr, this province was the autochthonous home of 

 this family, and Neumayr's opinion is strongly sustained by the remarkable series 

 of species described from the Northeastern Alps by Geyer, Hauer, and others, and 

 an especially fine series by Herbich from Siebenburgen. The Lytoceratidse are 

 by no means absent from the faunas of the Lower Lias in Central Europe, though 

 generally quoted as being found in the Middle and Upper Lias. Thus Amm. 

 Drkxni, Dumortier, and Amm. Salisburgense and Amm. alius of the same author, are 

 apparently members of this family, found in the Oxynotus bed of the basin of the 



1 Barrande, with all his knowledge and close study of the fossil Cephalopoda, has not been able to prove 

 a single example. Those he has given are readily explained as morphological equivalents, and we have 

 found by the investigation of Bohemian specimens that the Nautili of the present time are entirely different 

 from paleozoic forms. As soon as the naspionic and nealogic stages are studied and compared, they are 

 found to be distinct. This is also true of his Gon. (our Cekeceras) prmmaturum. 



2 Geol. Verhalt. d. Geg. nordw. v. Achen-See. 



