314 Ornithichnology. 



food. Their tracks of course/are numerous; andj 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 mud 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 



make 



of 



them w^ere produced by web-footed birds. The lateral distance of 

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



Ime of the bird s course, is much greater than that of any of the 19s- 

 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 irapres- 

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

 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 oC the step, six inches. This 



ordinary 



between the tracks of tliis 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. 



