90 GENESIS OF THE ARIETID A. 
they were probably taken from loose rock not in place, and may have come 
from a dark gray limestone in the horizon of Psil. caliphyllum or megastoma. 
They cannot, therefore, be considered forerunners of the psiloceran forms of 
the Planorbis bed. 
Neumayr’s and Wiihner’s researches, quoted below in Table VI. and in the 
chapter on “ Descriptions of Species,’ show that a wonderfully rich fauna of 
Psiloceratites and Caloceratites existed in the region of the Northeastern Alps ; 
but, so far as we know, there is nowhere any statement of the appearance in time 
of the discoidal radical Psi. caliphyllum or planorbe before Caloceras in that prov- 
ince, as there is in South Germany. The aspect of the fauna is older than that 
of South Germany ; but though composed of an assemblage of radical forms of 
Psiloceras, they occur side by side with Cal. Johnston and Schilot. catenata (subangu- 
lare of Wiihner), and are equivalent to the fauna of the Caloceras bed of South 
Germany, but not to the lowest Planorbis bed. Suess and Mojsisovics, in their 
table of strata in the mountains of the Osterhornes,' Northeastern Alps, describe 
a very thick Planorbis horizon, and in the uppermost bed they enumerate Psil. 
planorbe, supposed to be the English form ; also Psi. Hagenowi and Cal. Johnstoni, 
no fossils having been found in lower beds. Here again it is probably the 
Caloceras bed, and not the lowest Planorbis bed, which contained the fossils 
described. 
In South Germany Psiloceras planorbe, the radical species of the Arietide, is 
prevalent, as may be seen in collections, and in the works of all the geological 
writers on this region, especially Quenstedt. Quenstedt notes what he calls the 
Laqueum layer, and speaks of caloceran forms as having made their first appear- 
ance somewhat later in the Planorbis horizon than Planorbis itself, and in the 
“ Ammoniten der Schwabischen Jura” describes and figures a specimen, Planorbis, 
var. /eve, from the Bone-bed, which is placed by most writers in the Rheetic. 
In the neighborhood of Salin and Besan;on, Prof. Jules Marcou has shown 
that there is a deficiency in the Planorbis horizon, and lately Louis Rollier,? 
following in his footsteps, has confirmed these observations. Professor Mar- 
cou, however, at Boisset, near Salins, found a true Planorbis bed containing 
the typical species. W. A. Ooster, in the “Catalogue des Cephalopodes des 
Alpes Suisses,’* enumerates many species; but unluckily the beds are not de- 
fined. It is, however, evident that the collections in Switzerland which he 
examined, and the authors he quotes, did not give any data contradictory to 
Waagen’s conclusions, which we give below. 
Waagen, in his “ Der Jura Franken, Schwaben und der Schweiz,” says that 
outside of Suabia, whether going northeast or southwest, one finds nowhere the 
typical development of the Lower Lias as it exists in Suabia; and it is especially 
the lowest bed which is apt to be nearly everywhere starved out. This remark 
and the table given by Waagen are very important, and coincide with the 
results reached in this chapter. 
1 Gebirgesg. d. Osterh., Jahrb. geol. Reichsan., XVIII., 1868, p. 195. 
2 Form. Jurass. Soc. d’Kmulat. Porrentruy, 1883, p. 105. 
8 Denksch. schw. Gesellsch. Naturwissen., X VIII., 1861. 
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