MS The American Geologist. February, 1894 
The most important evidence was the observation, on the north slopes 
of Draper mountain, of three small bosses of the Shenandoah limestone 
projecting up through an extensive area of only slightly disturbed De- 
vonian shales ; these seem to furnish incontestible proof that the shales 
were laid down on a folded and eroded surface of Shenandoah lime- 
stone. 
This has a wide bearing on the structure of the entire province, for it 
marks a period of folding that occurred about the beginning of Devo- 
nian time and one in the Lower Carboniferous, and shows that a por 
tionof the valley was dry land during Devonian times. 
24. Titr Trias and Jura of the Western States. Alpheus Hyatt, 
Boston, Mass. The author announced the following results of his studies 
upon the fossils of these two systems: The Trias, or at least a Monotis 
fauna having the aspect of a member of the Trias, has been found by 
Dr. Curtice while collecting for the U. S. Geological Survey in American 
canon, south of Cisco, California. Just above this horizon there oc- 
curred a Daonella bed, and next above this a bed containing numerous 
Ammonitince. The Daonellce were supposed to be Triassic until it was 
found that they passed sporadically into the Ammonites bed. The Am- 
monitince are of doubtful affinity, and it was found impracticable to de- 
cide whether they are Liassic or Triassic, because no sutures are pre- 
served in any of the numerous examples. With these were also two 
species of rugose Aptychi not hitherto found below the upper Lias in 
Europe. 
The Mesozoic rocks of Sailor's canon and American canon to the 
lower limits of the Snow Mountain tuffs contain a similar fauna, and 
none of them are younger than the Lias nor older than the Trias. 
The announcement was made of the rediscovery of a number of Gabb's 
Triassic and Jurassic types, and among these were fossils from New 
Pass, Desatoya Mts., Nevada, which showed the occurrence of a fauna 
like that of Humboldt county to the west in Nevada, and that both 
are Muschelkalk. Gabb's types of Ammonites nevadamis and 
an associated species of Goroniceras, described as new, show the ex- 
istence of the lower Lias in Esmeralda county. Nevada, thirty miles 
from Walker's lake. A collection of fossils loaned by Prof. Thomas 
Condon of Eugene City, Oregon, contains species identical with some of 
those found at Taylorville, Cal., in the Hardgram sandstone of the Up- 
per Lias. Gabb's types also demonstrate the existence of the same 
sandstone at the Walker's lake locality, or Volcano, asGabb named that 
region; and the fauna of this horizon in the Upper Lias is found at all 
three of these widely separated localities. 
The fossils collected by the officers of the U. S. Geological Survey dur- 
ing the last four or five years represent the rocks of the western slope of 
the Sierra Nevada fairly well. These consist of Aucellce and Ammon- 
itince and some other less important and less characteristic fossils. The 
Ammonitince mainly belong to the genera Perisphinctes and Cardioce- 
ras, and these may be closely affiliated with species of the Russian 
faunas of the Upper Jura. The A ucellce associated more or less with the 
Ammonitince tell the same story. They are all striated species and 
quite distinct from the smooth forms of the Knoxville slates. The Au- 
cellce occur in similar association with < 'ardioceras and Perisphinctes in 
the faunas of the Upper Jura in Russia : and their relations to the spe- 
cies of the same genus in the lower part of the Knoxville slates show 
that the Gold Belt series contains older faunas. These fossils were 
mainly from Mariposa. Calaveras and Tuolumne counties in California. 
Gabb's type of Perisphinctes (Amm.) nevadanus was among those 
lately found, and it demonstrates, together with some other similar 
species collected by the U. S. Geological Survey near Colfax, that the 
dark slates of that region are also Upper Jurassic. 
[To be Continued. | 
