25 
[Hyatt. 
of the Arietidae (except Yermiceras) originated, is directly con- 
trary to all the testimony of paleozoology, and has in its favor 
only the earlier occurrence in that basin of Psil. planorbe and 
Schl. striatissima and catenata. 
Yermiceras has an independent history. The radical species of 
this genus, Cal. laqueum , appeared in South Germany in the Cal- 
oceras bed and probably migrated thence to the Northeastern Alps 
appearing in the modified form of Verm, praespiratissimum ( sp . 
Wahner) in the Angulatus bed of that fauna. This series also met 
with the most favorable opportunities for the evolution of new modi- 
fications in the faunas of South Germany and the Cote D’Or. The 
members of the genus found in the Mediterranean province are sim- 
ilar to the more degenerate forms of this genus and do not indicate 
the existence of very favorable surroundings in that basin during 
the Lower Lias so far as this series was concerned. 
The species of Arnioceras are not abundant or large in the North- 
eastern Alps basin, whereas they are very abundant and represented 
by large numbers of radical and progressive forms in the basin of 
South Germany and the Cote D’Or. The radical species also oc- 
cur in the Angulatus bed of these basins earlier than that of the 
Northeastern Alps. 
The radical species of Coroniceras occur on the Angulatus ho- 
rizon in all three of the faunas just mentioned, but the evolution 
of the new forms of the series and two sub-series, and the pres- 
ence of transitional forms, are marked characteristics of the faunas 
in South Germany and Cote D’Or and it is probable that it origi- 
nated in these basins in the province of Central Europe. 
Agassiceras Icevigatus and striaries appeared simultaneously and 
were about equally developed in the basins of the Cote D’Or and 
Rhone, but have not been found so early as the Angulatus bed in 
any other faunas. It seems more likely from this and the abun- 
dance of other forms of the series that it appeared first and was best 
represented in these two basins. 
The evidence with regard to Asteroceras is more doubtful. It 
may have first appeared in South Germany with Aster, obtusum in 
the Upper Bucklandi bed ; or, it may have been an exception to the 
general rule and appeared first in the residual fauna of Luxemburg 
where this species occurs on the same horizon. The collateral ev- 
idences, however, are in favor of South Germany. It has perhaps 
more remarkable degenerate forms in England than anywhere else. 
