262 REPORT OP THE AMERICAN COMMITTEE. 
beds presenting the faunal characters of the Keuper or upper 
Trias of that continent. They, however, present two divisions 
which are lithologically distinct in Nevada, to which Mr. King 
has given the names Koipato to the lower and Star Peak to the 
upper. The latter is of marine origin, while the Trias of the 
Rocky Mountains and of the Atlantic slope is lacustrine. The 
Rocky Mountain Trias is exposed upturned along both the eastern 
and western slopes of north and south ranges, and the north and 
south slopes of east and west ranges. In Nevada it forms the 
mass of the Havalla, Pah Ute, and West Humboldt ranges. Its 
thickness is, according to King : 
Feet. 
Colorado, east flank of mountains, . . . . 300 to 1200 
Nevada, Koipato bed, 4000 to 6000 
Nevada, Star Peak bed, 10,000 
Triassic beds probably also occur in the Indian Territory.* 
JURASSIC SYSTEM. 
The vertebrate fauna is characterized as follows : 
Present : Reptilia Dinosauria Opisthocoela, Orthopoda, Meso- 
suchia; Testudinata Clidosterna; Ichthyopterygia Sauranodon- 
tidse ; Batrachia Anura ; Mammalia ? Bunotheria. Absent : 
Pisces Actinochiri, Saurodontidse ; Percoraorphi ; Dinosauria 
Belodontidse ; Reptilia Choristodera ; Aves Odontornithes ; 
Mammalia Placentialia Ungulata, Creodonta, and Tillodonta. 
The Jurassic bed constantly overlies the Triassic along the 
flanks of all the Rocky Mountain ranges, consisting of clays, 
shales, marls, and cherty limestones. In Colorado it has, accord- 
ing to King, a thickness of seventy-five to two hundred and fifty 
feet. It grows thicker westward, reaching seven hundred feet 
on the west flanks of the Sierra Madre, in New Mexico, and, 
according to King, consists in Nevada of 
Feet. 
Slates, 4000 
Limestone, 1500 to 2000 
The forms of vertebrates found apparently together at this 
horizon are represented in Europe by genera of different sub- 
* Triassic formations have not yet been detected in Texas, those recently 
referred by Mr. Hill of the United States Geological Survey to that age being 
the Permian beds of the Red River (see Amer. Jour. Set., 1887, p. 302). 
