1895. | NEW YORK ACADEMY OF SCIENCES. a, 
Hartshorne dips southwardly. The first suggestion is that a 
fault brings up the limestone, but the more probable condition 
is that of overturned anticlinals, as the anticlinal structure is 
very distinct in the ridges. One bed was discovered just before 
our return to Hartshorne, which will yield an abundant harvest 
to a skillful and patient collector. The specimens obtained at 
the outcrop are in poor condition and suffice only for determi- 
nation of the genera. Prof. R. P. Whitfield recognized in them 
Zeacrinus, Fenestella, Humetria, Athyris, Nucula, Yoldia and 
Cladodus, with characters referring them to the Upper Carboni- 
ferous. This series of ridges is continuous into Arkansas and 
is the guide to the coal prospector working eastwardly in Indian 
Territory. The coal measures are reached again south from 
them, but no mining operations have been undertaken there. 
The only limestone seen by the writer above this mass is a 
thin bed observed along the Missouri, Kansas and Texas rail- 
road south from Savannah, and again on the same road south 
from the limestone ridge near Atoka. Dr. Chance found a fos- 
siliferous limestone on the Choctaw railroad east from Hart- 
shorne. 
From the Arkansas line to McAlester, this coal field has an east 
and west strike and the structure, as pointed out by Dr. Chance, 
is Appalachian. One finds here a series of short, overlapping 
anticlines enclosing typical canoe-shaped synclines, termed by 
Dr. Chance the Mitchell, McKinney, Grady and McAlester 
basins. The dips are comparatively gentle, 5 or 6 degrees, 
where the axes overlap, but become 50 or even 60 degrees along 
the sides of the basins. And this condition continues for pos- 
sibly 25 miles westward beyond McAlester. As one approaches 
McAlester from the east, the overlapping anticlines become 
stronger and the basins more numerous, so that the outcrop of 
the coals reaches further south. To what extent the Limestone 
ridge is affected by these local folds cannot be determined dur- 
ing a hasty ride, for the petty ridges composing it are not per- 
sistent, having suffered so much from erosion, so that one might 
easily be misled as to the direction. It is certain, however, that 
the ridge, as a whole, is bent southwestwardly from Wilburton 
on the Choctaw railroad to Limestone Gap, on the Missouri, 
Kansas and Texas road, in accordance with the widening of the 
coal area. 
At Limestone Gap, 27 miles south from McAlester, the rail- 
road passes through the Limestone ridge and thence runs but 
little off the strike almost to Atoka, 46 miles south from Mc- 
Alester. On the southerly side of the ridge the rocks are dip- 
ping almost southeastward at not more than 30 degrees. But here 
