WOEHNEEOCEEAS AND SCHLOTHEIMIA. 93 



than in South Germany. Tate and Blake x discuss the conditions of the deposi- 

 tion, and arrive at the conclusion, that " it seems probable that no portion of the 

 liassic beds was formed in very deep water, but that even the shales partook of 

 the nature of submerged mud flats." 



Psil. Hagenowi occurs in the Northeastern Alps, North Germany, Bohemia, and 

 Switzerland ; and in all these places the true Psil. planorbe, var. leve, is scarce. 

 This form is a degraded modification of planorbe which may have arisen inde- 

 pendently in each locality, and it indicates that this species probably lived under 

 unfavorable conditions in these regions. Caloceras was, however, strongly rep- 

 resented in the same basins. It formed an unbroken procession, so far as Gal. 

 Johnsioni was concerned, from the Northeastern Alps to England. 



The facts, with certain exceptions, of which we shall take note farther on, 

 appear to indicate that Psiloceras was autochthonous in the Northeastern Alps. 

 It probably appeared as a radical or chronologic migrant from the Trias, and 

 gave rise to Caloceras in the Lias. Thence both series may have spread by 

 chorological migration into the basins of South Germany, the Cfite d'Or, Switzer- 

 land, North Germany, and England. During these migrations they met with 

 favorable conditions in some localities, and unfavorable conditions in others ; 

 hence the inequalities of representation. In both series, however, it is obvious 

 that it was the discoidal species which settled in the new territories to the west 

 of the Mediterranean province. It thus becomes evident that the more highly 

 specialized and more involute species were probably not the progenitors of any 

 of the derivative series that subsequently arose, — an inference agreeing exactly 

 with all our conclusions with regard to the radical nature of discoidal, as com- 

 pared with involute forms. 



W^EHNEROCERAS AND SCHLOTHEIMIA. 



The exceptionally rich fauna of the Angulatus (Megastoma) bed given by 

 Wanner 2 contains, besides the distinctive Wsehneroceran series, Schlot. angulata, 

 and other forms of the same series, as well as many of the involute Psilo- 

 ceratites and keeled Caloceratites, mentioned above. This assemblage shows 

 undoubtedly that a region so richly populated must have been exceptionally 

 favorable for the evolution of Waehneroceras, and possibly also the autochtho- 

 nous home of Schlotheimia. The announcement by Neumayr 3 of Waagen's 

 discovery of a true Schlot. angulata in the Bhsetic beds near Parthenkirchen 

 in the Mediterranean province, should be mentioned in this connection. Suess 

 aud Mojsisovics show that the Angulatus zone is very slightly developed 

 in the Osterhornes mountains, but it contains Psil. longipontinum, Cal. laqueam, 

 Schlot. angulata and Moreana, besides a possible Cor. kridion, identified as similar 

 to that figured by Dumortier in France. This assemblage, therefore, contains 

 the most important of the species found in other regions in the Caloceras bed, 

 as well as in the true Angulatus bed above. 



1 Yorkshire Lias, p. 215. 2 Unter Lias, loc. cit., IV., 1886, p. 199. 



3 Jahrb. geol. Reichsans , 1878, XXVIII. p. 64, and Abh. geol. Reichsans., VII. p. 44. 



