98 GENESIS OF THE ARIETIDA. 
kridion as occurring in the Angulatus beds, and figures a specimen.’ According 
to Fraas’s collection, Cor. kridion certainly appeared in South Germany in the 
Angulatus bed at Méhringen, and Quenstedt declares it to be a rare form in the 
Bucklandi zone. Coroniceran forms are so numerous in the Bucklandi zone of 
South Germany and France, that it becomes difficult to determine whether they 
were more fully evolved in the one or the other of these basins. 
Wright’s tables and lists show that the English fauna was by no means so 
rich in numbers of species and varieties as either the French or South German ; 
and this result, notwithstanding the great size and multitude of specimens found 
in the various localities of that basin, confirms our experience in the study of 
collections while in England. 
The works of North German paleontologists show less thinning out of the 
forms of this series in that direction than in any of the preceding genera. The 
names bisulcatus, multicostalus, and the like, occur frequently. This suggests that 
in bucklandian times the species of the Arietidse had become hardier and more 
able to survive in the unfavorable localities to the northward, or else the sur- 
roundings themselves had changed and become more favorable. There is one 
fact, however, favoring the former as the most probable conclusion. The speci- 
mens are neither very abundant, nor are they so large, nor so generally dis- 
tributed in North Germany as in South Germany. 
The radical of the third subseries of Corniceras, Cor. Sauzeanum, did not appear 
earlier than the Upper Bucklandi bed in any fauna, not excepting that of the 
Mediterranean province Chapuis and Dewalque show that Cor. Sauzeanum per- 
sisted in the Luxemburg region, and that Cor. bisuleatum and mullicostatum were 
also present ; but the number of forms found there are certainly very limited. 
Schlénbach mentions the usual fauna of the Buckiandi zone in Brunswick, but 
the species are not so numerous as in South Germany, and no note is made of 
their abundance. The absence of the Tuberculatus bed, or its unfossiliferous 
character when present, is noted by Schlénbach, and this indicates a decrease in 
number of forms as compared with other regions. Brauns in “ Hannoverische 
Jura,” and Emerson in “ Liasmulde von Markoldendorf,’ show that the coroni- 
ceran series is represented, but is not remarkable for the number of species, and 
in most. localities, so far as we can learn, the species of this series are not 
abundant. Shliiter cites Cor. rofiforme and Cor. Gmuendense as occurring in the 
Bucklandi zone of the Teutoburger Wald, and his descriptions support these 
results. He alludes to other forms than these species, but does not enumerate 
them. 
The poverty of the later beds of the Lower Lias in North Germany, and the 
constant recurrence of unfossiliferous strata, are characteristics similar to those 
of the basin of the Northeastern Alps, and these facts indicate that similar un- 
favorable conditions obtained there. 
Dumortier’s work enables us to see, also, that in the Rhone basin on the 
southern side of the Cote d’Or the fauna thinned out. Thus, though Cor. kridion 
1 Pl Sv ig. 3, 4. 
2 See Mojsisovics’s mention of the zone of Amm. Sauzei, Gebirgsgr. d. Osterhornes, p. 199. 
