OXYNOTICERAS. 101 
does possess Ast. acceleratum, a form found nowhere else except in the Cote d’Or. 
Quenstedt’s collection at Tiibingen is very fine, and his descriptions and figures 
indicate a full representation of species, though Codlenoti is not present. 
Chapuis and Dewalque show that the Luxemburg rocks contain several differ- 
ent forms of the genus, though they are not so numerous as in South Germany 
or England. Schlénbach shows that there is an odfusus horizon in North Ger- 
many containing the usual forms, but only fossiliferous in certain localities, and 
Brauns publishes similar results in his work. This horizon according to Schliiter 
does not appear to have been represented in the Teutoburger Wald, unless his 
Gmuendense bed and the broken beds mentioned on page 48 of his work be con- 
sidered the equivalent of all the beds between the Angulatus and Raricostatus 
horizons. 
The English fauna, according to Wright’s “ Lias Ammonites” and the collec- 
tions examined by me, has all the principal forms, and often very large shells, 
and there are also, as in the Cote d Or and Rhone basins, representatives of the 
extreme modification of this genus, As?. Collenoti. 
This series had, therefore, a more general development in all the basins we 
have considered than any of the preceding series, but in spite of this there seems 
to be a preponderance of forms in favor of England and France. The unusual 
case of an early appearance of the radical species Ast. obfuswm in the Luxem- 
burg region should have its ‘due weight, but the evidence of an equally early 
occurrence in the South German basin shows that Ast. obtusum probably made 
its appearance as an autochthone upon the level of the Upper Bucklandi bed in 
the South German basin, and was thence distributed. It is probable that the 
series subsequently met with more favorable conditions in the Cote d’Or and in 
England than in any other basin. 
> 
OXYNOTICERAS. 
Oxynoticeras oaynotum, the radical species of its peculiar series, appeared in 
such profusion and with such excessively compressed and involute whorls in 
the Northeastern Alps, South Germany, the Cote d’Or, and England, that one 
seems to be dealing with contemporary migrants from some unknown fauna. 
With regard to this conclusion, however, it may be well to be cautious. The 
morphological gap is not so great as appears between an adult of a species like 
Oxyn. oxynotum, and Agas. striaries or levigatum. This is indicated clearly by the 
development of the individual in Ast. obfusum, oxynotum, and Agas. Scipioncanum, 
as we have tried to show in the previous pages and in the descriptions of the 
genera and species.! Ozyn. oxynotum was a species with a highly accelerated 
development, and in such forms the departure from allied forms took place sud- 
denly. In consequence of this abbreviated mode of evolution gaps were left in 
the series which it is difficult to fill. The evidence with regard to the connec- 
tion of Ast. Collenoti with Ast. obtusum and the young forms of Ozyn. oaynotum, 
1 See young of Oxyn. oxynotum, pl. x. fig. 4, 5, and 14-17, and Summ. PI. xiii. fig. 9, 10, and compare 
with Agas. levigatum, pl. viii. fig. 9, 10, and striaries, pl. ix. fig. 14, 15. 
