SUMMARY. 113 
Jum become simpler with advancing age, and more like those of planorbe, and by 
the scarcity of the latter, which, though found by Wihner," is declared to be rare. 
One of Wihner’s specimens was transitional to Hagenowi in its sutures, and this 
indicates that the province of the Northeastern Alps was the autochthonous 
home of caliphyllum, planorbe, and Hagenowi, and adds greatly to the probabilities 
in favor of Neumayr’s hypothesis. In Cal. Liasicum, Johnstoni, and nodotianum it 
is common to find varieties varying in the sutures between the Mediterranean 
and Central European extremes of modification, the latter being of course the 
most numerous in their own province and rare in the Northeastern Alps. The 
sutures of Liusieum,? tortilis, and nodotianus,s when contrasted with Quenstedt’s, 
Wright's, and our own figures, give a good idea of the extent of variation, which 
is quite as great as in Psi. planorbe, if not greater. 
Undoubtedly these facts, and the nearer approximation in aspect and sutures 
of the Mediterranean forms of Psiloceras to Gymnites of the Trias, the genus we 
have always regarded as the probable ancestor of the former, are strongly in 
favor of Neumayr’s opinion that the forms of the European province arose by 
chorological migration from the apparently more ancient fauna of the Mediter- 
ranean province. The richer evolution of triassi¢ forms in the Mediterranean 
province, as described and illustrated by Mojsisovics, can also be brought forward 
in favor of this view. Nevertheless, it is not right to yield entirely to the fasci- 
nations of this opinion until there is positive proof that Psil. planorbe or caliphyllum 
occurred earlier in this province than in Central Europe. 
With regard to the origin of Caloceras from this province, the facts are still 
stronger in favor of Neumayr’s view, but Vermiceras appears to have arisen in 
South Germany. 
With regard to the origin of Wehneroceras and Schlotheimia, it seems prob- 
able from the zovlogical evidence that they also arose in the Mediterranean prov- 
ince. The evidence is, however, geologically incomplete, since it is probable 
that Schiot. catenala occurred quite as early in South Germany. Weebhneroceras, 
the series of connecting forms uniting Schlotheimia and Psiloceras in this same 
province, is not yet proved to be of as ancient origin as Schlotheimia itself, and 
this introduces an anachronism which requires additional facts for its explanation. 
Mosch ® has decided that the Lias to the west of the head-waters of the Rhine 
contains species peculiar to the Central European province. W. A. Ooster’s 
descriptions and figures of species confirm this conclusion, since he does not men- 
tion any novel species, though he describes twenty-one forms, representing more 
or less all the genera of the Arietide.® 
Zittel’ remarks that there is great resemblance between the Upper Lias in 
Provence and Lombardy. Mojsisovics,’ in quoting these observations, says that 
1 Verh. k. k. geol. Reichsans., 1886, p. 169. 
2-D'Orb., Terr. Jurass., I. pl. xlviii. 8 Ibid, pl. xin. 4 Ibid., pl. xlvii. 
5 D. Jura Alpen d. Ost-Schweiz, 1872, p. 1. 
® Cat. des Ceph. des Alpes Suisses, Denk. schweiz. Gesellsch. Naturwis., XVIII., 1861; see also Studer, 
Geol. d. Schweiz, II. p. 231, for similar views. 
7 Central-Appenn., Geogn. pal. Beitr., Beneke, II. p. 174. 
8 Dolomit Riffe Siid-Tyr. und Venet., p. 26. 
15 
