314 Ornithichnology . ' 



food. Their tracks of course, are numerous; and, were the mud to 

 be suddenly hardened into stone, they would scarcely be distinguish- 

 ed from some of the tracks on the sandstone In the immediate vicin- 

 ity. Indeed, in one instance, the process was well nigh completed: 

 for the water had fallen several feet and left the mu^d with the tracks 

 exposed for some weeks to the sun in a dry season ; so that it was 

 almost as hard as stone ; and had I taken a cast of the impressions, 

 as I might have done, I am sure it would easily have passed for the 

 tracks in sandstone.* I merely took a sketch of a few of the impres- 

 sions, which is given in Fig. 14. I could not, however, but feel, 

 that I was witnessing a repetition of the very process by which the 

 tracks in the stone were produced. 



Fig. 12, is a sketch of two steps of the common goose, (Anas 

 Canadensis) on mud. The length of the foot is four inches, and of 

 the step, seven inches. The space beneath the web connecting the 

 toes, is quite obvious on the mud ; it being sunk below the general 

 level, but not so deep as the toes. The entire absence of any such 

 appearance in the fossil tracks, makes it almost certain, that none of 

 ^hem were produced by web-footed birds. The lateral distance of 

 the successive tracks in Fig. 12, to the right and left of the central 

 line of the bird's course, is much greater than that of any of the fos- 

 sil tracks of the same size. 



Eig. 13, exhibits the tracks of a bird, probably of the genus Te- 

 trao, which I met with last summer ; but I caught only a glimpse of 

 it. The length of the foot, not including the hind toe, is one inch 

 and a half, and of the step, five inches. 



Fig. 14, has already been referred to, as exhibiting the steps of a 

 small species of snipe, wanting in the hind toe. Its foot is only an 

 inch long, and its step two and a half inches. The same tracks are 

 shown in Fig. 11, laid off from the same scale as the fossil impres- 

 sions in the first two figures, in order to exhibit their relative size in 

 respect to the fossil foot marks. 



Fig. 20, shows a case of the tracks of the domestic hen (Phasia- 

 nus gallus) in mud. The foot, without including the hind toe, is 

 nearly three inches long; the length of the step, six inches. This 

 is the ordinary distance between the tracks of this species. Only 

 the alternate track shows the hind toe ; owing to the foot's not sink- 

 ing deep enough in all cases. 



♦ Such tracks as are the subjects of this paper. 



