12 ON THE FOSSIL FOOT-MARKS 



known that this formation encircles entirely in a peculiar manner, all the three anthracite 

 coal basins of Pennsylvania, and Prof. Rogers so describes it, stating that " it is enclosed 

 between the ridges of Formation No. 9, on the one side, and on the other, those contain- 

 ing Formation No. 12, composing the margin of the coal measures." (2d Report, p. 66.) 

 He describes "Formation No. 12," as "conglomerates and sandstones immediately below 

 the coal," and states it to repose on the "Red Shale Formation," (No. 11,) p. 67. 



A mass of coal plants exists immediately on the northern face of the heavy conglome- 

 rate, here tilted ten degrees over the vertical, and forming the crest and "back-bone" of 

 Sharp Mountain. This conglomerate mass is about one hundred and fifty feet thick at 

 the western side of the road, below Pottsville. On the same road-side, about 1735 feet from 

 these coal plants, is the face of the rock bearing these " foot-prints," tilted slightly over 

 the vertical, and facing the north. It is proper to state, that the limestone of the Old 

 Red Sandstone exists here about two feet thick, and underlies these "foot-prints" sixty- 

 five feet. 



Sauropus primjEvus. PI. XXXI. 



Feet pachlydactylous. Anterior ones armed with five toes. Divarications of the first 

 and second toes = 60°; of the second and the third, = 50°; of the third and the fourth, 

 = 40°; of the fourth and the fifth, = 40°. Impression of the toes too much confused 

 to measure correctly, varying from one and a half to two inches long. Length of the 

 foot about three and a half inches. Breadth about three inches. Distance from the point 

 of the first to the second toe, 1.9 inches; from the second to the third, 1.4 inches; from 

 the third to the fourth, 1.2 inches; from the fourth to the fifth, 1 inch. Posterior feet 

 armed with four toes. Divarications of the first and second, = 40; of the second and 

 third, = 35°; of the third and fourth, = 50°. Length of the toes not ascertainable, owing 

 to their obliteration by its impact with the impression of the anterior foot. Track of the 

 posterior foot in a line and directly in advance of the anterior foot. The stride or step 

 from toe to toe, 13 inches; from outside to outside, 8 inches. Length of the tail-marks, 

 about 5 inches; breadth, three-quarters of an inch. 



Plate XXXII. 

 This presents a reduced view of the slab, which is thirty-four by twenty-one inches, or 

 rather less than one-fourth the natural size, and displays the regularity of the steps in a 

 double row, as well as the librating tail-grooves, and the ripple-marks. 



Plate XXXIII. 

 In my former communication to this society, I mentioned that there were other remains 

 of organized matter in this rock. Obscure impressions of plants, small spots, with fila- 

 mentous radiations and reed-like marks had been observed. In many places on the sur- 

 face of the rocks, I observed rough nodules, concretionary masses, which I have since 

 concluded may be fossil ova of batrachian reptiles. They are irregular ovoid bodies, and 

 usually in pretty close approximation. In the specimen before me, the water in passing 

 over these left lines indicating its direction. (Fig. 2.) Occasionally may be seen small 



