GEOGRAPHIC RELATIONS OF TRIAS OF CALIFORNIA 785 
latus Hauer, T. torquillus Mojs., T. Telleri Mojs.,and many others 
characteristic of the Tuvalic substage. Inthe Hallstadt beds of 
the Tyrol no such association as this is known; the 7rachycerata 
do not occur higher up than the Julic substage, zone of Tyachy- 
ceras aonoides, nor does the Subbullatus fauna appear below the 
Tuvalic. It is, therefore, a question as to whether the Julic 
fauna survived longer here than elsewhere, or whether the Z7vop- 
ates subbullatus fauna reached here earlier, in middle Karnic time. 
There is not yet enough evidence to decide this, but it all points 
to the latter alternative. The Zvofites fauna is an immigrant 
fauna wherever known, appearing suddenly without local ances- 
tors in the Alps, the Himalayas, and in California, in the upper 
part of the Karnic stage; thus it may be that its occurrence in 
California marks an earlier appearance, for it was probably 
endemic in the American region. In addition to this, the 
Trachycerata associated with the Subbullatus fauna all belong to 
the subgenus Protrachyceras, which is supposed to be character- 
istic of a lower horizon than T7vachyceras itself, which genus has 
recently been found in the Upper Karnic of the Himalayas. 
Further, the Subbullatus fauna did not all reach California at the 
same time, Homerites semiglobosus Hauer, not appearing here until 
all the Zyachyceras fauna, and most of the Zrofites, with which it 
is associated in the Alps, had become extinct. 
We have in this occurrence an interesting study in homotaxis; 
the Zrachyceras fauna is homotaxial all over the world, so is the 
Subbullatus fauna, and yet their occurrence together proves that 
neither fauna was synchronous in its appearance in various parts 
of the earth, and that even the order of appearance of the two 
faunas is not the same in all regions. 
The most comprehensive review that has appeared on the 
faunal geography of the Upper Trias is the chapter by Dr. E. 
von Mojsisovics, ‘‘Die Meere der Trias-Periode,’’* in which all 
that is known of the distribution and relations of faunas of this 
period is given, and several pages devoted to the western Ameri- 
™Denkschriften d. K. Akad. Wiss. Wien, Bd. LXIII, 1896, “ Beitr. z. Kenntniss 
d. Obertriadischen Cephalopoden Faunen des Himalayas.” 
