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 Arn. falcaries, but it had some tran- 
sitional characters allying it with Arn. miserabile and also with Arn. semicostatum. 
Arnioceras did not appear at all in the Angulatus zone, but in the Bucklandi 
zone of the Rhone 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 dOr, and they appear to have been wholly migrants, not 
possessing the numerous varieties ohgervable in South Germany and at Semur. 
Only one, or at most two, species of Arnioceras, called either obdiquecostatus of 
Zeiten, or geometricus 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. Schliiter gives, however, a lengthy descrip- 
tion and figures of Aim. obliquecostalus 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 Arn. oblusiforme, one to miserubile 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 Céte 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. rotiforme. Cor. datum also occurs in company with 
these, but is the radical of another subseries of this genus. Oor. 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. brsuleatum. Hauer’s work,’ 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 Paléontologiques du Basin du Rhone,” gives Cor. 
1 Nordostlichen Alpen, Denk. Akad. Wien, XT. 
13 
