CHAP. XXXVII.] FOSSIL FOOT-PRINTS IN COAL STRATA. 233 



therium, so called by Professor Kaup, because the marks 

 both of the fore and hind feet resemble the shape of a 

 human hand. Now in these European hand-shaped 

 foot-marks, both the hind and fore feet have each five 

 toes, and the size of the hind foot is about five times 

 as large as the fore foot ; but in the American fossil 

 (fig. 13), the posterior foot-print is not nearly twice 

 as large as the anterior, and the number of toes is 

 unequal, being five in the hinder and four in the 

 anterior foot. In the Greensburg animal, as in the 

 European Cheirotherium, the fifth toe stands out near 

 ly at a right angle with the foot, and somewhat resem 

 bles the human thumb. On the external side of all 

 the Pennsylvanian tracks, both the larger and smaller, 

 there is a protuberance like the rudiment of another 

 toe. The average length of the hind foot is five and 

 a half inches, and of the fore foot four and a half. 

 The fore and hind feet being in pairs, follow each 

 other very closely, there being an interval of about 

 one inch only between them. Between each pair 

 the distance is six to eight inches, and between the 

 two parallel lines of tracks there is about the same 

 distance. 



In the case of the European Cheirotherium, whether English 

 or German, the hind and fore feet occur in pairs, but they form 

 only one row, as in fig. 14, in consequence of the animal having 

 put its feet to the ground nearly under the middle of its body, and 

 the thumb-like toes are seen to turn to the right and to the left 

 in the alternate pairs. But in the American tracks, which form 

 two parallel rows, all the thumb-like toes in one set turn to the 

 right, and in the other set to the left. We may infer, therefore, 

 that the American Cheirotherium belongs to a new genus of 

 reptilian quadrupeds, wholly distinct from that which characterizes 

 the triassic strata of Europe, and such a generic diversity might 

 have been expected in reptilian fossils of such different ages. 



The geological position of the sandstone of Greensburg is per 

 fectly clear, being situated in the midst of the Appalachian coal- 



