178 [December, 1S44. 



spherical, and about one and a half inches across it. The track is four 

 inches in its transverse and conjugate diameters. In the specimen before 

 us, the ball of the foot is situated in the centre, the toes spreading regu- 

 larly around it ; but in some it stands out behind and completes the digital 

 circle. 



No. 7. Thenaropus ovoidactylus. Toes 

 5, ovoid, spreading about 240°. This is 

 evidently the track of a very large ani- 

 mal. Each toe is about an inch long, 

 and their spread near six inches. The 

 ball of the foot is about two and a half 

 inches across it. 



The stone on which these tracks were found has an exposed surface of 

 fifteen by twenty feet, rising like the other rocks in the neighborhood to the 

 west, and dipping at a small angle to the east. It is a coarse grained sand 

 stone, about 150 feet beneath the largest of our coal seams, and near 800 feet 

 beneath the topmost stratum of our coal formation. From the fact of the 

 existence of numerous holes or pots, some of which will hold fifteen or 

 twenty gallons, excavated, as we know they are at the present day, by the 

 whirling of pebbles, set in motion by a running stream, I infer that the stone 

 must have lain in the bed of a river which was subject to partial periodical 

 desiccation. These pots, which bear a striking resemblance to those now 

 found in our neighboring rivers, particularly the, Yonghiogheny, were the 

 objects of curiosity to the people of the neighborhood for years; but the 

 tracks, though often noticed, were comparatively unimportant, as they pre- 

 sumed they were made by dogs, bears, wild turkeys, and other animals 

 belonging to the present order of animated nature. 



To the geologist, however, they are of more interest. He looks through 

 the long vista of time which has elapsed since the stone on which these tracks 

 are now found was plastic sand or arenaceous mud — contemplates its con- 

 solidation into stone — the subsequent excavation of these pots by whirling 

 pebbles — the deposition of sandstone, limestone, shale, and numerous beds of 

 coal, amounting, in all, in this vicinity, to about 800 feet. And after all 

 these various changes, which required hundreds, end perhaps thousands of 

 years to accomplish, he views with his mind's eye the vast agency, the over- 

 whelming power, which doubtless convulsed the whole western continent, 

 contorting the crust of the earth, and upheaving our vast Apalachian 

 chain of mountains, extending from New York to Alabama, and at the same 

 time throwing the main strata into beautiful folds, or elongated anticlinal 

 roots. And finally, he contemplates the slow upheaval of the continent from 

 the bed of the primeval ocean — the subsidence of the waters — the quiescence 

 of the earth — and the various successive races of animals and plants, both 

 visible and microscopic, which preceded the present order of animated 



