AGASSICERAS. 99 
appeared in the Angulatus zone, the number of species on the bucklandian hori- 
zon was evidently more limited than in South Germany, Semur, or England. 
The coroniceran series, therefore, seems to have arisen on the same level in 
the Mediterranean province, in the South German basin, and probably in the 
Céte d’Or. The radicals of the subseries, so far as known, do not follow the same 
law. Cor. datum has not yet been mentioned or described as occurring in any 
other basin than the Cote d’Or. Cor. Sauzeanum occurs, however, in northwest- 
ern Germany, according to Braun, and in the South German, Cote d’Or, and 
English basins in the Upper Bucklandian bed, though in the basin of the Rhone 
and Mediterranean province it is not recorded with certainty from any level 
earlier than the Tuberculatus beds. 
It is possible that Cor. kridion may have originated in the Northeastern Alps, 
but Neumayr and Wiihner have not yet found this species in their researches 
among the fossils of the Angulatus zone, and no good figure has been published. 
The early occurrence and large number of varieties and species in the collections 
at Stuttgardt and Semur, and the numerous transitional varieties, also show that 
Cor. kridion found its most favorable home either in the South German or the 
Cote d’Or basin. The earlier occurrence of the radical of the third subseries, 
Cor. latum, at Semur, indicates the Céte d’Or to have been the centre of distri- 
bution for the Bucklandi subseries. The occurrence of Cor. Sauzeanum on the 
same level in South Germany, Cote d’Or, and England shows, together with the 
number and variety of the forms subsequently evolved, that the centre of dis- 
tribution of the Bisulcatus subseries lay in one or the other of these basins. 
This conclusion accords with the origin and distribution of the parent series, 
Arnioceras, and derives additional support from this fact. It is evident also, 
from these facts, that the Mediterranean province must be regarded .as having 
been peopled with migrants from the province of Central Europe, so far as relates 
to the subseries of this genus, and this makes it more likely that the radical spe- 
cies of the whole series, Cor. kridion, also arose in this province. So far as known 
its appearance in the Angulatus horizon of the Northeastern Alps is not sup- 
ported by the presence of transitional forms, nor by the presence of Arnioceras in 
the same horizon. The species, if a real éridion, certainly must be provisionally 
regarded as a chorologic migrant from the west. 
AGASSICERAS. 
Agas. levigatum appeared in the Angulatus zone of the Semur collection, and 
was represented by numerous specimens in this fauna. It is also attributed to 
this horizon in the basin of the Rhone by Dumortier, and is well figured by him. 
In South Germany Agas. levigatum did not appear until the Upper Bucklandi 
bed. In England and North Germany it appeared associated with planicosta 
above the Bucklandi horizon. This radical species, therefore, according to our 
present knowledge, was a migrant in all of these basins, derived probably from 
the Cote d’Or or the Rhone basin. 
1 Etudes Pal., pl. xviii. fig. 5, 6. 
