UPPER CARBONIFEROUS ey 
Nevada. I have examined the fossils in question only casually, and 
it has been many years since I have seen them at all, but I doubt 
whether in this instance, any more than the other, the evidence war- 
rants saying more than that they are possibly non-marine. 
The Upper Carboniferous faunas of the West appear to be better 
differentiated than those east of the Rocky Mountains. At least three 
well-marked facies can be recognized. ‘The oldest of these is found 
in the limestones whose occurrence has already been mentioned, resting 
directly upon Lower Mississippian limestones of similar character 
in Arizona and probably in Utah. This fauna is succeeded by one 
which is best considered from its development in the Transpecos region 
of Texas, because it is there more highly developed, more favorably 
studied, and more determinable in its stratigraphic relations with 
higher beds. It occurs in the Hueco formation which is 5,000 feet 
thick, and is practically calcareous throughout. As has already been 
noted, the Hueco formation by overlap rests upon the pre-Carbonif- 
erous in this region. The Mississippian faunas, together with the 
earlier Pennsylvanian ones, appear to be absent. The Hueconian 
fauna is widely distributed over the West, ranging indeed into Alaska, 
while it is even recognizable in Asia and eastern Europe. Most of 
the occurrences of Carboniferous in the West can be referred to this 
series, although some or them present more or less distinctive facies. 
The more important of the facies provisionally referred to the Huecon- 
ian are these: that of the Aubrey group of Arizona, rather widely 
distributed; that of the phosphate beds of the Preuss formation, local 
in Utah, Idaho, and Wyoming; the Spirijerina pulchra fauna with a 
considerable distribution in Idaho, Wyoming, Utah, and Arizona; 
the fauna of the McCloud limestone of California probably extending 
into Nevada; and that of the Nosoni formation of California (in 
part the “ McCloud shale”), apparently recognizable to the eastward 
and to the North and West, even into Alaska. 
In the Transpecos the beds of the Hueco formation are succeeded 
by those of the Guadalupe Mountains. The contact between the 
Hueco formation and the Guadalupian series is obscured by faulting 
and by desert deposits, but it is assumed that the interval between 
the highest known beds of the one and lowest known beds of the other 
is not a long one and that no unconformity exists between them. The 
