THE FOSSIL FOOTMARKS OF THE UNITED STATES. 191 



batrachians once lived, as well as tridactyle quadrupeds, — tridac- 

 tjle at least on the fore foot. 



Table of the Ratio between the several Characters of Group II., on a 



Scale of 100. 



Group III. 



Toes four ; three pointing forward ; the hind toe lying on the 

 inside of the foot and on a prolongation backward of the outer toe. 



Genus VI. ORNITHOPUS. 



Characters the same as for the Group. 



Species 1. Ornithopus Adams anus. (PI. VII. Fig. 5.) 



Ornithoidichnites Dance, Am. Jour. Science, Vol. XLVII., Plate 

 4, fig. 5. 



No. 125 in Cabinet. 



Divarication of the lateral toes, 100° ; of the inner and middle 

 toes, 40° ; of the middle and outer toes, 60° ; of the middle and 

 hind toes, 140°. Length of the middle toe, 6.5 inches ; of the 



