208 AN ATTEMPT TO DESCRIBE THE ANIMALS THAT MADE 



and middle toes, 25^ ; of the outer and middle toes, 35°. Length 

 of the middle toe (measured on the chord), 3.2 inches ; of the inner 

 toe, 2 inches; of the outer toe, 1.6 inch; of the middle toe beyond 

 the rest, 2.2 inches. Distance between the tips of the lateral toes, 

 3.5 inches ; between the inner and middle toes, 1.7 inch; between 

 the middle and outer toes, 3.4 inches. Versed sine of the inward 

 curvature of the inner toe, 0.3 inch ; of the middle toe, 0.6 inch. 

 Outer toe straight. Width of the curved ridge between the toes 

 and heel (the space between the dotted line and the heel, in Plate 

 14, fig. 3,), 0.3 to 0.6 inch : the length of the same (which is the 

 width of the foot at the roots of the toes), 2.2 inches. Length 

 of the heel (breadth literally), 1.2 inch. Breadth of do., 2 inches. 

 Length of the foot, 4.7 inches ; of the step, 8 to 12 inches, if con- 

 sidered a biped. Foot vaulted, so as to leave a ridge between the 

 toes and the heel, and hence the specific name. Axis of the foot 

 very much turned inward towards the line of direction. Distance 

 from that line, 5 inches. Track shown, of the natural size, on 

 Plate 14, fig. 3. 



Remarks. — The specimen, Plate 14, fig. 3, from which most 

 of the above description was taken, is a very perfect one, from 

 Turner's Falls, presented to me by Mr. Ptolemy P. Severance. 

 But just as I was sending this paper to the press (April 27th), my 

 attention was called to a slab of ten tracks in a row, or rather two 

 rows, lying in the sidewalk in Greenfield Street, in front of the 

 residence of Franklin Ripley, Esq. It was from the Horse Race, 

 and is a gray micaceous sandstone. I at once recognized these 

 tracks as essentially corresponding with those of the H. concamera- 

 tus. They are distinguished from all others by the axis of the foot 

 turning so much inward toward the line of direction, by the great 

 distance of the middle of the heel from that line (5 inches), and by 



