THE FOSSIL FOOTMARKS OF THE UNITED STATES. 237 



also brought to view a long heel on the hind foot. Of the fore 

 foot I had insulated and perfect specimens, from which the sketch, 

 Plate 16, fig. 6, was taken. Plate 22, fig. 6, shows the position 

 and character of all the tracks on the slab, the front ones being 

 now in a great measure ground away. This discovery renders 

 it necessary to remove this species from the genus Palamopus, 

 which is supposed to be composed of bipeds. It approaches 

 so near the Macropterna in its general character, that I place it 

 there provisionally. Yet both feet have four toes ; but it would 

 not be strange if the other species of this genus should be found 

 to have a short toe on the fore feet ; so that I do not think this 

 fact a sufficient reason for referring the M. recta to another ge- 

 nus. There is somewhat the appearance of a toe running obliquely 

 backwards from the end of the heel of the hind foot, where are 

 placed dotted lines on Plate 15, fig. 6. But I am not sure of it, 

 and, besides, it seems to be on the outside of the heel, which is a 

 presumption against its being a toe ; as the hind toe usually pro- 

 ceeds from the inside of the heel. 



Species 3. Macropterna divaricans. (PI. XV. Fig. 7.) 



Fine specimens in the cabinet of Mr. Dexter Marsh in Green- 

 field, and in that of Professor Shepard in Amherst College. 



Hind feet. — Tetradactylous. Divarication of the outer toes, 

 90° to 100°; of the inner and second, 25°; of the second and 

 third, 35°; of the third and fourth, 32°. Length of the inner toe, 

 0.45 inch ; of the second, 0.6 inch ; of the third, 0.7 inch ; of the 

 fourth, 0.6 inch ; of the heel, 1.2 inch ; of the foot, 1.9 inch ; of 

 the step, 3.3 inches. Heel somewhat wedge-shaped, varying in 

 Avidth from 0.2 to 0.6 inch. Distance from tip to tip of the 

 lateral toes, 1.3 inch; from the inner to the second toe, 0.55 inch; 



