282 STUART WELLER 
In the Mauch Chunk series of earlier authors, Stevenson! recog- 
nizes three members, a lower the Tuscumbia, a middle the Maxville, 
and an upper the Shenango. ‘Toward the close of Pocono time there 
was a marked contraction of the sea in the Appalachian Basin, just as 
was the case at a corresponding time in the Mississippi Valley Basin. 
This contraction was of such proportions that the Tuscumbia beds 
were not deposited in Ohio in the area occupied by the earlier Waverly, 
except at the Kentucky border, but, as in the west, there was a read- 
vance of the sea until it had reached its maximum extent in the deposi- 
tion of the Maxville limesione which is to be correlated essentially with 
the Ste. Genevieve limestone of the Mississippi Valley. Such a cor- 
relation would make the Tuscumbia essentially contemporaneous with 
the St. Louis limestone of the Mississippi Valley, a correlation which 
is sustained by the paleontologic evidence. The Shenango is said to 
contain fossils characteristic of the Chester of the Mississippi Valley,” 
and may be correlated with that formation. 
MISSISSIPPIAN FAUNAS OF THE ROCKY MOUNTAIN BASIN 
In Montana and elsewhere in the northern Rocky Mountain region, 
limestones of Mississippian age are widely distributed, although but 
little data in regard to the faunas have been published. The most 
notable contribution to our knowledge of these faunas is that of Girty 
on the Carboniferous fossils of the Yellowstone National Park. The 
faunas here described are distributed through more than 1,600 feet of 
strata of the Madison limestone, but they do not show any such differ- 
entiation as 1s recognized in the Mississippi Valley. One general fauna 
persists with but minor changes throughout the entire series and this 
fauna shows many affinities with the southern Kinderhook faunas of 
the Mississippi Valley, as well as with the fauna of the Salem lime- 
stone. Faunas allied to that of the Salem have also been detected 
elsewhere in the region, as the Idaho fauna noted by Meek and the 
fauna of the Yakinikak limestone already mentioned. These relations 
suggest that in this northwestern region a long-lived fauna, having 
more or less close relationships with the Salem fauna, was contem- 
poraneous with the larger part of the entire Mississippian series of the 
1 Op. cit., p. 85. 
2 Stevenson, op. cit., p. 85. 
3 Monograph, U.S. G. S., XXXII, Pt. 2, pp. 479-599. 
