THE FOSSIL FOOTMARKS OF THE UNITED STATES. 185 



Remarks. — I acknowledge it to be possible that a distinct heel 

 may belong to this genus, although my specimens do not show it. 

 In that case, the first species, A. Reclfieldianum, would not dif- 

 fer enough from the Steropezoum ingens to be separated from it, 

 although some of its characters do not well agree with that species. 

 But as I have seen quite a number of specimens of the tracks of 

 most of the species of this genus, and no very distinct heel is vis- 

 ible, although some of the impressions are quite deep, I group them 

 under a distinct genus ; and if that should fail, yet all the species 

 will maintain their ground as distinct species of Steropezoum, ex- 

 cept the first. 



Species I. Argozoum Redfieldianum. (PI. VI. Fig. 1.) 



Ornithoidichnites Redfieldii, Am. Jour. Science, Vol. XLVII., 

 Plate 3, fig. I. 



Nos. 145, 146, 149, in Cabinet. 



Divarication of the lateral toes, 75° ; of the inner and middle 

 toes, 30° ; of the middle and outer toes, 45°. Length of the middle 

 toe, 12 inches ; of the inner toe, 8 inches ; of the outer toe, 9.5 

 inches ; of the claw, 2 inches ; of the foot, 12.5 inches ; of the 

 step, 30 inches. Distance between the tips of the lateral toes, 12 

 inches ; between the inner and middle toes, 7.8 inches ; between 

 the middle and outer toes, 9 inches. Length of the middle toe be- 

 yond the others, 6 inches. Versed sine of the inward curvature 

 of the middle toe, 0.7 inch. Track shown, of the natural size, on 

 Plate 6, fig. 1. 



Locality. — Chicopee Falls, on hard, quartzose, and sometimes 

 calcareous, gray sandstone. 



Dedicated to my friend, William C. Redfield, Esq., of New 

 25 



