CORONICERAS. 97 



the bucklandian horizon, and their early appearance in the Angulatus zone of 

 Cote d'Or, show that this was their most favorable home. We have identified 

 the earliest occurring Semur specimen with Am. falcaries, but it had some tran- 

 sitional characters allying it with Am. miserabile and also with Am. semicostalum. 

 Arnioceras did not appear at all in the Angulatus zone, but in the Bucklandi 

 zone of the Ehone basin, if Dumortier's work can be considered as authoritative 

 upon this question. This fauna also possesses specimens of much larger size than 

 any found elsewhere, and the series is quite as fully, though perhaps not so 

 richly, represented as in the basin of the Cote d'Or. 



In England there are certainly fewer species and forms than in South Ger- 

 many or the Cote d'Or, and they appear to have been wholly migrants, not 

 possessing the numerous varieties observable in South Germany and at Semur. 



Only one, or at most two, species of Arnioceras, called either obliquecostatus of 

 Zeiten, or geomeiricus after Oppel, appear to have been found in North Germany. 

 Making all due allowances for negative evidence, this appears to indicate a very 

 slight representation of the genus. Schluter gives, however, a lengthy descrip- 

 tion and figures of Amm. obliquecostatus as occurring in a bed between the Angu- 

 latus and the Bucklandi zone in the Teutoburger Wald, and his description and 

 figure show that this species may be in reality divisible into several, — one simi- 

 lar to Am. obtiisiforme, one to miserabile or semicostatum, and perhaps another with 

 more marked keel and channels. The forms are confined wholly to this stratum, 

 which may belong either to the Angulatus or the Bucklandi bed. The Luxem- 

 burg fauna was equally poor. 



This genus, therefore, certainly does not have the aspect, as far as is now 

 known, of having originated in or near the basin of the Northeastern Alps. The 

 evidence is rather in favor of its having arisen from small planorbis-like forms, 

 occurring first either in the Cote d'Or or in the South German basins. At pres- 

 ent the evidence is not determinative, though somewhat in favor of the former 

 basin. The series subsequently migrated to the Mediterranean province, making 

 its first appearance there in the Upper Bucklandi zone. 



CORONICERAS. 



In company with the first arnioceran species at Semur is a doubtful form of 

 Cor. kridion, and later in the Scipionis bed a true Cor. kridion is found together 

 with a representative of Cor. roliforme. Cor. latum also occurs in company with 

 these, but is the radical of another subseries of this genus. Cor. kridion is cited 

 by Suess and Mojsisovics from the Osterhornes mountains as occurring in the 

 Angulatus zone, and this is not a difficult species to identify. The Coroniceran 

 forms as cited by the same authors in the Bucklandi zone are represented only 

 by Cor. bisuleatum. Hauer's work, 1 however, shows that this is probably only a 

 local peculiarity, though the fauna is not so rich as that of either South Germany, 

 France, or England. 



Dumortier, in his " Etudes Paleontologiques du Basin du Rhone," gives Cor. 



1 Nordbstlichen Alpen, Denk. Akad. Wien, XI. 

 13 



