262 THE OLDEST AIR-BREATHERS 



have been uniformly referred to as the first observations of 

 this kind. Insects and Arachnidans, it may be observed, had 

 previously been discovered in the coal formation in Europe. 



The original specimen of these footprints is still in the 

 collection of the Geological Survey of Canada, and a cast 

 which Logan kindly presented to me is exhibited in the Peter 

 Redpath Museum of McGill University. It is a slab of dark- 

 coloured sandstone, glazed with fine clay on the surface ; and 

 having a series of seven footprints in two rows, distant about 

 three inches ; the distance of the impressions in each row being 

 three or four inches, and the individual impressions about one 

 inch in length. They seem to have been made by the points 

 of the toes, which must have been armed with strong and 

 apparently blunt claws, and appear as if either the surface had 

 been somewhat firm, or the body of the animal had been 

 partly water-borne. In one place only is there a distinct mark 

 of the whole foot, as if the animal had exerted an unusual 

 pressure in turning or stopping suddenly. One pair of feet 

 the fore feet, I presume appear to have had four toes touching 

 the ground ; the other pair show only three or four, and it is 

 to be observed that the outer toe, as in the larger footprints 

 discovered by Dr. King, projects in the manner of a thumb, 

 as in the cheirotherian tracks of the Trias. At a later date 

 another series of footprints, possibly of the same animal, was 

 obtained at the same place by Prof. Elder, and is now in the 

 Peter Redpath Museum. Each foot in this shows five toes, 

 and it is remarkable that the animal was digitigrade and took 

 a long step for its size, indicating a somewhat high grade 

 of quadrupedal organization. No mark of the tail or belly 

 appears. The impressions are such as may have been made 

 by animals similar to some of those to be described in the 

 sequel. 



Shortly afterward, Dr. Harding, of Windsor, when examining 

 a cargo of sandstone which had been landed at that place from 



