202 TWENTY-FOVRTH REPORT ON THE StATE MuSEUM. 



tracks," varying in size from a little more than one inch to full nine 

 inches in diameter, and, at first sight, so astonishingly like the 

 impression left in soft mud or sand by the unshod foot of a horse, 

 as to fully excuse almost any amount of credulity on the part of the 

 ordinary observer. On close examination, however, the resemblance 

 soon disappears, from the many points of dissimilarity which can be 

 detected ; such as the great height of the protuberance representing that 

 which would be formed by the hollow of the foot, and the perfectly 

 rounded margin of the cavity, like what would be left by the removal 

 of a rounded, crescent-shaped body. 



In examining a number of these tracks, several were observed where 

 the substance forming them had been imbedded vertically in the 

 strata, leaving a cavity representing a transverse section of the body 

 removed, as shown in the accompanying wood-cut. The long diame- 

 ter of this cavity was about six inches; the 

 distance across the widest part of the bulb 

 a little more than two inches, while the 

 distance across the neck was less than half 

 an inch, the depth of the cavity over three 

 inches, and the larger portion extending 

 beneath forming the segment of a circle; 

 showing very conclusively that the body forming the cavity con- 

 sisted of a thickened, rounded rim, having a thinner membrane occu- 

 pying the intermediate space. Another specimen observed had been 

 imbedded obliquely, and preserved the cavity representing a greater 

 part of the disc. In this case the depressions on the sides of the 

 disc had been very deep, allowing the rock to approach within about 

 a fourth of an inch in the center. 



From the evidences furnished by specimens of this character, the con- 

 clusion was drawn that the impressions had been formed by the tuber- 

 ous root of a marine plant ; and on searching over the surfaces of the 

 blocks some were found that were quite thickly covered with impres- 

 sions of a reed-like plant, which, although much injured and defaced 

 from the action of fire and weathering, were still distinct enough to 

 place beyond doubt their vegetable origin. • On other blocks were 

 found the same plant-stems passing vertically into the sandstone. 



Believing, from the foregoing facts, that these bodies are of vegeta- 

 ble origin, the generic name Hippodophycus is proposed for them, 

 in allusion to the peculiar impressions left by their removal. 



