THE FOSSIL FOOTMARKS OF THE UNITED STATES. 179 



Species 2. ^thyopus minor. (PI. IV. Fig. 2, 3.) 



Ornithoidichnites fulicoides, Trans. Assoc. Amer. Geo!., Plate 

 11, fig. 4. 



Nos. 60-62, 130, 136, 137, 159, 209, in Cabinet. 



Divarication of the lateral toes, 50^ to 70° ; of the inner and 

 middle toes, 20° to 30° ; of the middle and outer toes, 30° to 40:. 

 Length of the middle toe, 3.2 inches ; of the inner toe, 2.5 inches ; 

 of the outer toe, 2.9 inches ; of the foot, 3.5 to 4 inches ; of the 

 step, 8 to 10 inches ; of the claw, 0.7 inch. Distance between 

 the tips of the lateral toes, 3.3 inches ; between the inner and 

 middle toes, 1 .9 to 2 inches ; between the middle and outer toes, 

 2.5 inches. Projection of the middle toe beyond the lateral ones, 

 1.5 inch. Width of the toes, 0.65 to 0.87 inch. Length of the 

 first phalanx on the inner toe, 1.2 inch ; of the last two, 0.5 inch ; 

 of the first on the middle toe, 1 inch ; of the second, 0.5 inch ; of 

 the last two, 0.7 inch ; of the first on the outer toe, 0.8 inch ; of 

 the second, 0.7 inch ; of the third, 0.6 inch ; of the last two, 0.5 

 inch. Toes straight, winged : claws normal, winged. Angle of 

 the axis of the foot from the line of direction, from 5° to 10° ; 

 sometimes outward, and sometimes inward. Distance between the 

 heel and the line of direction, 1.25 inch. Track shown, of the 

 natural size, on Plate 4, figs. 2 and 3, which differ chiefly in size. 



Localities. — Turner's Falls and South Hadley. 



Remarks. — There is one supposition which would make the 

 distinction between Brontozoum and ^thyopus an accidental cir- 

 cumstance. Mud, when trodden upon, may be in so plastic a state, 

 that deep impressions made upon it would be partially filled by the 

 gravity of the surrounding particles. Yet a superficial impression 

 might remain, say of the foot of an animal, and this, becoming 

 hardened, might present the appearance of winged toes. Of the 



