GIRTY, THE GUAD ALU PI AN FAUNA 
137 
Delaware Mountain formation and the Capitan limestone of the trans-Pecos 
section. Although the faunal relation between the Delaware Mountain 
and Capitan faunas on the one hand and the Artinskian and Permian 
faunas on the other was by no means as close as between the Hueconian and 
Gschelian, it seemed justified to correlate in a tentative manner the two 
American horizons with the two Russian ones, which appear to occupy the 
same position in the section. Carried to a logical conclusion, it is apparent 
that these comparisons, if correct, would place the entire invertebrate-bearing 
Carboniferous section of Kansas — Pennsylvanian and Permian as well — 
below not only the Russian Permian, but even the Artinskian, and align it 
with the Gschelian and underlying beds. 
While these correlations seemed measurably supported, or at least not 
contradicted by the evidence in hand, it was fully appreciated that the rela¬ 
tions suggested were on trial and must be verified by more complete data 
before they could be accepted. R was clearly appreciated also that the fun¬ 
damental proposition from which these correlations proceeded — those with 
the Mississippi Valley at least —that the peculiarities of the Guadalupian 
fauna were due to time not to environment, must be decided by further 
explorations. The most promising field for this purpose was toward the 
north, for in this direction, as represented on the imperfect maps of the 
region, the Guadalupe Mountains, from whose southern point the rich and 
interesting faunas were obtained, in their northward extension merge with 
the Sacramento Mountains, the western face of which swings westward until 
it reaches a point nearly north of El Paso. From the more northern ex¬ 
tension of these Mountains we have had fossil evidence for many years, the 
faunas, however, presenting a facies very unlike the Guadalupian. The 
question as to what becomes of the Guadalupian rocks and faunas in the 
northward extension of the mountain mass whose southern end is composed 
of them was discussed many times with Mr. Bailey Willis and Mr. G. B. 
Richardson with whom I have had the pleasure of being associated in much 
of my work in the trans-Pecos region. Although several trips have been 
made to that area during the past five or six years, it has always been for a 
specific purpose and with a limited allotment and it seemed, to me at all 
events, that when the exploration in question was taken up, it should be 
made thorough and should be reasonably unhampered by considerations of 
time and expense. 
In the meantime the evidence represented by our scattered and uncor¬ 
related data in the Sacramento Mountains was accounted for by the hypoth¬ 
esis of erosion and deformation, for, if it seemed probable that the faunal 
differences of the Guadalupian from the Kansas section were not the result 
of environment, it was a fortiori improbable that corresponding differences 
