17 
[Hyatt. 
General Meeting, May 16, 1888. 
The President, Prof. F. W. Putnam, in the chair. 
The following papers were read : 
EVOLUTION OF THE FAUNAS OF THE LOWER LIAS. 
BY ALPHEUS HYATT. 
This paper is a short abstract of a chapter on the geological and 
faunal relations of the Arietidae prepared for a forthcoming memoir 
upon that family. According to my classification this group com- 
prises the Angulatus group, which I formerly placed in a distinct 
family, the genus Psiloceras, the normal forms generally supposed 
to belong to the Arietidae by all authorities, and also the remark- 
able genus Oxynoticeras, which I formerly classified as a separate 
family, and which is very generally referred to the Amaltheus group 
by other authors. The inclusion of so many important forms 
makes the Arietidae, from our point of view, so large that it con- 
tains the vast majority of all the lower Lias Ammonitinae, and it 
becomes necessarily the source, or ancestral focus for all the later 
formed groups of the Ammonitinae 1 of the Jurassic in Europe. There 
are many more or less complete lists and monographs of local fau- 
nas in the province of Central Europe, and extensive collections 
which afford a solid basis for comparison. The preliminary work 
of Prof. Jules Marcou 2 in synchronizing the minuter subdivisions 
of the Jura in Central Europe was completed by the more extensive 
application of the same principles by Oppel 3 , who visited, studied 
and synchronized the faunas of the different localities .and identi- 
fied the same beds in a large part of this province. The illustrated 
publications of Hauer 4 , Neumayer 5 , Wahner 6 , Geyer 7 and Herbich 8 
have also thrown a strong light upon the peculiarities of the faunas 
of the eastern part of Europe, particularly the basin of the North- 
2 The Ammonitinae do not include Lytoceras or Phylloceras, etc. Such forms have 
been placed by the author in a distinct sub-order, the Lytoceratinae. 
2 Roches des Jura, p. 23, 162, 173 etc. 
3 Die Jura-Format. Eng. Franr. u. d. siidwestl. Deutschl. Wiirtt. Jahresh., vol. 12-14, 
1856. 
4 Die Cephal. a. d. Lias d. norostl. Alpen, Denksch. K. Akad. d. Wissensch., vol. 11. 
5 See note 4, p. 587. 
6 Mojsis. et Neum. Beitr. vols. 2, 3, 4, 5. 
7 Ceph. Heirl. Schich, Ahh. k. k. geol. Reiehsan., vol. 12. 
8 Das Szeklerland, Mitt. Jahrb. d. lc. ungar. Anst., vol. 5, pt. 2. 
PROCEEDINGS B. S. N. H. 
VOL. XXIV 
JULY, 1888. 
