438 MUSCHELKALK AND FOSSILS. [Ch. XXIL 



controlled by the decided opinion as to the order of superposition to 

 which the most able living surveyors of the Austrian Alps have come, 

 we should naturally take for granted, when presented with such a sec- 

 tion as that given at p. 435, that the Muschelkalk, if it happened to 

 be present at Hallstadt, would have overlaid the bed No. 3, instead of 

 having to be intercalated between Nos. 3 and 4, or even placed below 

 No. 4. 



Whatever ambiguity may still remain in many minds respecting the 

 precise chronological relations of the St. Cassian beds, no one ques- 

 tions that they are Triassic, and they have entirely dissipated the no- 

 tion formerly entertained as to the marine fauna of the whole Triassic 

 era having been poverty-stricken. The St. Cassian fauna, moreover, 

 leads us to expect that, should we hereafter have an opportunity of 

 studying the marine fossils of the lowest division of the Bunter sand- 

 stone, the present break between the Palaeozoic and Neozoic forms will 

 almost entirely disappear. 



Muschelkalk. 



The next member of the Trias in Germany, the Muschelkalk, 

 which underlies the Keuper before described, consists chiefly of a 

 compact grayish limestone, but includes beds of dolomite in many- 

 places, together with gypsum and rock salt. This limestone, a forma- 

 tion wholly unrepresented in England, abounds in fossil shells, as the 

 name implies. Among the Cephalopoda there are no belemnites, and 

 no ammonites with foliated sutures, as in the lias and oolite as well 

 as in the Hallstadt beds ; but we find instead a genus allied to the 

 Ammonite, called Ceratites by De Hann, in which the descending 

 lobes (see a, b, c, fig. 470) terminate in a few small denticulations point- 





Ceratites nodosus. Muschelkalk. 



a. Side view, b. Front view. 



c. Partially denticulated outline of the septa diving the chamhers. 



ing inwards, the saddles being plane. Among the bivalve shells, the 

 Posidonia minuta, Goldf. (Estheria minuta, Bronn), (see fig. 471), is 

 abundant, ranging through the Keuper, Muschelkalk, and Bunter- 



