CHAP. XXXVII. ] IN COAL STRATA. 311 



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, whe 

 ther 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 Ame 

 rican tracks, which form two parellel 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 characterises the triassic strata of Europe, 

 and such a generic diversity might have been ex 

 pected in reptilian fossils of such different ages. 



The geological position of the sandstone of Greens- 

 burg is perfectly clear, being situated in the midst of 

 the Appalachian coal-field, having the main bed of 

 coal, called the Pittsburg seam, three yards thick, a 

 hundred feet above it, worked in the neighbourhood, 

 and several other seams of coal at lower levels. The 

 impressions of Lepidodendron, Siyillaria, Stigmaria, 

 and other characteristic carboniferous plants, are 



