136 
ANNALS NEW YORK ACADEMY OF SCIENCES 
evidence shows the facts to be otherwise. It was, therefore, the conservative 
course to assume that the very great difference between the Guadalupian 
faunas and those of the Mississippi Valley was due to time rather than to 
environment. The one fact then known which was unfavorable to this 
hypothesis was the apparently very limited distribution of the fauna, which, 
in the typical area, occupied nearly 4,000 feet of strata. At one time or 
another I have examined Carboniferous collections representing very many 
different horizons and scatteringly representing most of the areas in North 
America where Carboniferous rocks are known. If the strikingly individual 
facies of the Guadalupian fauna was not due to environment, why, I asked 
myself, did it not occur in other areas. The thickness of the series would 
diminish the chance of existence without discovery and the characteristic 
aspect of the fauna would diminish the chance of discovery without recogni¬ 
tion. To these questions it was possible to answer that certain scanty 
faunas in California did show some of the notable features of the Guada¬ 
lupian facies and it was also suggested that aside from such factors as 
non-deposition and erosion the apparent absence of this horizon might be 
accounted for by its representation elsewhere by non-fossiliferous strata, 
such as the “Red Beds” for the most part are. 
Now, if the difference of facies from the more eastern faunas was due to 
time, it seemed probable that the Guadalupian fauna was younger rather 
than older than the faunas of which we have knowledge in the Mississippi 
Valley. This seemed to be indicated by certain intrinsic features, such as 
the degenerated condition of certain brachiopods, as well as by the obvious 
relationship with certain Asiatic and European faunas, whose position was 
recognized as high up in the Carboniferous section. Confirmatory evidence 
was also found in a fauna beneath the Guadalupian, occupying some 5,000 
feet of rocks, which has a facies markedly different from the Guadalupian 
fauna and very much more in agreement with the familiar faunas of Kansas 
and the Upper Mississippi Valley. By reasoning such as this, the conclu¬ 
sion was suggested that the Guadalupian fauna was younger than any of the 
Pennsylvanian or “Permian” faunas of the Mississippi Valley. 
It has already been remarked that the Guadalupian fauna, while totally 
different from almost anything else known in the United States, or even in 
the western hemisphere, yet showed certain Asiatic and European affinities. 
The fauna of the underlying Ilueco limestone, while more comparable to the 
Pennsylvanian faunas of the Mississippi Valley than are those of the Guada¬ 
lupian series (Capitan and Delaware Mountain formations), is rather 
Russian than American in its facies. It shows marked resemblance to the 
Gschelian fauna of the Russian section. The Gschelian lies beneath the 
Artinskian and Permian of Russia, just as the Hueconian lies beneath the 
