Ornithichnology. 323 



of the step ten inches. The tracks exist on this stone in rehef, and 

 are very distinct. Dr. Dwight informs me, that one has been bro- 

 ken off; and this is supphed in the figure by dotted hnes. 



The rock from which Fig. 8 was taken, is a gray micaceous sand- 

 stone, or rather shale, brought from the Horse Race, and now form- 

 ing a flagging stone, in the village of Deerfield. The foot is about 

 four inches long, and the toes are a good deal divaricate, and there 

 appears no scopiform appendage behind. The average length of 

 the step is twelve inches. The third track is nearly obliterated, and 

 it appears that the bird moved in a somewhat curvilinear direction. 



It will probably be suggested, that O. diver sus, with all its varie- 

 ties, was made by the young of the species that produced O. ingens. 

 And I confess, that it is not easy to point out any other distinction 

 than in size. But my specimens of O. ingens are {ew, and much 

 more imperfect than those of O. diversus ; so that it is only in their 

 general features that I can compare the two species ; and I suspect, 

 that better specimens would bring to light other differences. For I 

 can hardly believe that the young of a bird, with a foot sixteen inch- 

 es long, would accompany their mother, in search of food, along the 

 margins of estuaries, while their feet were only two inches long, if, in- . 

 deed, they could ever have been so short as this ; and I hope to show, 

 in another place, that all these tracks must have been made by birds, 

 thus wading along the shores of estuaries or lakes. Besides, the O. 

 diversus is fifty times more common than the O. ingens ; and can we 

 suppose, that in such circumstances, such a great disproportion would 

 exist between the old and the young birds ? Is it so with living spe- 

 cies ? I suspect it is not, although I confess myself but little ac- 

 quainted with the facts in the case. 



O. tetradactylus. Length of the foot, exclusive of the hind toe, 

 from two and a half to three and a half inches. Toes divaricate ; 

 more slender than in O. diversus ; the hind one turned inward, so 

 as to be nearly in the line of the outer toe, prolonged backward. A 

 space, however, usually remains, between the heel and the hind toe, 

 as if its insertion were higher on the leg than the other toes, and its 

 direction obliquely downwards. Length of the step, ten to twelve 

 inches (?) Hairy appendage wanting. At the Horse Race. Proba- 

 bly several kinds of birds are embraced under this description, for 

 the size of the tracks, and especially the direction of the hind toe, 

 vary considerably. Indeed, in existing birds, these differences are 

 sometimes the only marks, exhibited by their tracks, between dif- 

 ferent species and genera. In the tracks of the domestic hen, 



