86 Dr. Duncan on the Fooi-marhs of Animals 



sions— I mean those of animals in the act of ascending. 

 Not many tracks, however, have been found, oi' \> hich the 

 prints are so well defined, and several of them belong evi- 

 dently to animals of diiierent species. I am myself ac- 

 quainted with five or six varieties which are clearly distin- 

 guishable — the largest of them indicating a quadruped of 

 such considerable magnitude, that the distance between the 

 impression of the hind foot and that of the corresponding 

 fore foot, is more, if I am not greatly mistaken, than a 

 yard and a half. 



But there is another class of impressions which must be 

 referred to the tracks of animals in the act of decending the 

 steep face of the stratum. These are not less numerous than 

 the other, but, for an obvious reason, they are not so easily 

 recognized to be the prints of feet. The steep face of the 

 stratum has caused the animals to slide in their descent, so 

 that in most instances nothing is observable but the rut made 

 by the heels of their fore paws, and sometimes also a slight 

 mark of their hind paws, which must have rested lightly on 

 the surface, while the animals were sliding their fore paws 

 alternately downward, and sinking them in the sand to secure 

 their footing. 



Of both of those kinds of impressions, traces may at this 

 moment be observed in the uncovered strata of the quarry, 

 though there are none of a very striking character which have 

 not been removed. The best specimins I have seen are in 

 the summer-house at Ruthwell. 



With regard to the species of animals whose tracks have 

 been so wonderfully preserved, I am happy that as to three 

 of them I can give the conjectures of a much more compe- 

 tent judge than myself, one of the first geologists of the age, 

 Professor Buckland, with whom I have been in correspon- 

 dence, having favored me with his opinion on the subject. 

 That eminent individual, supposing the sandstone to have 

 been deposited at an era when according to the received 

 opinion, no animals existed on our earth of a higher order 

 than reptiles, was induced to look to our present crocodiles 

 or tortoises as the species most nearly resembling those of 

 whose footsteps I sent him casts ; and on making experi- 

 ments with some live tortoises which he has in his possession, 

 he has come to the conclusion, that to animals of this spe- 

 cies the tracts belong. With regard to the sliding impres- 

 sions in particular, he says that he fully adopts my theory 



