Hyatt.] 
18 
[May 16 
eastern Alps. All of these researches, and many others not men- 
tioned, have made still farther advances in the classification of the 
minuter subdivisions or beds practicable. 
The principles of geographic distribution first announced by Jules 
Marcou 1 have also been vindicated by Neumayer 2 who has defined 
the homozoic bands of life in the faunas of what he has denomi- 
nated the Mediterranean, Central European and Russian provinces. 
The province of the Mediterranean according to this author in- 
cludes the Jura in southern Portugal, southern and southeastern 
Spain, a part of southeastern France, the Alps in Italy and Aus- 
tria, the Carpathians, and the Balkans farther to the east. The 
province of Central Europe includes all the remainder of France 
and Germany, England, the lands about the Baltic, the neighbor- 
hood of Briinn, and Krakau, and perhaps the neighborhood of the 
Dobrudsclia. The Russian province includes central Russia, Pets- 
chora land, Spitzbergen and Greenland. According to this author 
these comparatively well-known areas are parts of homozoic bands, 
which encircled the globe during the Jurassic period, respectively 
representing the boreal, temperate and tropical relations of the 
faunas now existing on its surface. 
All the forms of the Arietidae except Oxynoticeras have been 
traced by the united work of Quenstedt, Neumayer and myself in 
the fauna of Central Europe to Psiloceras planorbe and this species 
by Neumayer and the author has been united with its still more 
primitive congener, Psil. caliphyllum , in the Northeastern Alps. 
Neumayer took the ground that all of the normal forms of the 
Arietidae were derived from the more ancient though apparently 
contemporaneous fauna of the Northeastern Alps. I take great 
satisfaction in being able to corroborate this opinion, so far as the 
more important or radical series of the Arietidae are concerned, but 
propose a still farther improvement in these views by excepting cer- 
tain series from this law which I think originated in the basins of 
Central Europe. Before, however, this question can be considered, 
it will be essential to pass in review the author’s classification, 
which has made it possible to follow out the chorological migra- 
tions of the forms of the Arietidae more minutely than has been 
1 Op. cit. p. 74-91, 230, etc. 
2 Ueber Juraprov. Verb. k. k. geol. Reichsan., 1871, p. 54 ; Ueber unverm. auftret. Ce* 
phal. Jahrb. geol. Reichsan., vol. 28, 1878, et Jurastud. ibid, vol. 2, 1871, p. 524. 
