THE FOSSIL FOOTMARKS OF THE UNITED STATES. 201 



opinion, the impression of two feet nearly in the same spot ; one of 

 them a right foot, and the other a left. If they were those of a 

 quadruped, however, they ought to be both right or both left. I 

 regard the toes «, b, c, as belonging to the fore foot, and d as its 

 fourth or lateral toe ; while e, /, g, are the three front toes of the 

 hind foot, and h is its hind toe, which, on this layer, is much more 

 oblique to the heel than on the upper layer, Plate 10, fig, 1, as I 

 have observed to be the case in other instances, and which I im- 

 pute to a slight onward movement in the mud, as the track was 

 filled up. I at first regarded this specimen as a distinct species 

 from the P. longipes. But the resemblance is too close between 

 them to allow of a separation. The dimensions of the two tracks 

 on Plate 10, fig. 2, are, however, considerably different, as the fol- 

 lowing statement of their dimensions will show : — 



Fore foot. — Divarication of the lateral toes, 75° ; of the inner 

 and middle toes, 35° ; of the outer and middle toes, 40° ; of the 

 middle and hind toes, 70°. Length of the middle toe, 2.8 inches ; 

 of the inner toe, 1.6 inch; of the outer toe, 1.8 inch ; of the hind 

 toe, 1 inch. Distance between the tips of the lateral toes, 2.4 

 inches; between the inner and middle toes, 1.8 inch ; between the 

 outer and middle toes, 2.1 inches; between the middle and hind 

 toes, 3.5 inches. Length of the middle toe beyond the rest, 1.6 

 inch. Toes somewhat bent. 



Hind foot. — Divarication of the lateral toes, 80° ; of the inner 

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

 middle and hind toes, 115°. Length of the middle toe, 2.2 inches ; 

 of the inner toe, 1.5 inch ; of the outer toe, 1.7 inch ; of the hind 

 toe, 0.7 inch. Distance between the tips of the lateral toes, 2.2 

 inches ; between the inner and middle toes, 1 .4 inch ; between the 

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