Two New Species of Fossil Footmarks. 51 



15°. Length of the middle toe, 2 to 3 inches ; do. of the inner 

 toe, 1-5 to 2 inches; do. of the outer toe, 1-8 to 2*3 inches; do. 

 of the claw of the middle toe, 0*4 inch ; do. of the foot, 3 to 3-5 

 inches ; do. of the step, 13 to 29 inches. Width of the toes, 0-33 

 to 0*5 inch; do. of the posterior part of the foot, 1 to 1*4 inch. 

 Longest diameter of the double-headed lower extremity of the 

 tarso-metatarsal bone, 0*5 ; shortest do., 0*27 inch. Length of the 

 middle toe beyond the outer ones, 1-2 to 1-4 inch. Distance be- 

 tween the tips of the lateral toes, 15 to 1-6 inch; do. between 

 the inner and middle toe, 137 to 1-64 inch ; do. between the out- 

 er and middle toe, 1-2 to 1*65 inch. Length of the first phalanx 

 of the inner toe, 0*65 to 0*8 inch ; do. of the second and third, 

 (supposed to make but one impression,) 06 to 0*8 inch; do. of 

 the first of the middle toe, 0-04 to 8 inch ; do. of the second 

 phalanx, 0*53 to 0*8 inch ; do. of third and fourth, 0-4 to 0*8 inch ; 

 do. of the first of the outer toe, 0*4 to 0*54 inch ; do. of the sec- 

 ond, 0*3 to 0-4 inch; do. of the third, 0*26 to 0*35 inch; do. of 

 the two last, 0*33 to 0'45 inch. Tracks in a right line, and the 

 axis of the foot coincident with that line. 



Distinctive Characters. — The most striking characters by which 

 the tracks of this animal are marked off from all others, are the 

 near approach to parallelism of the lateral toes, and the great 

 length of the step compared with the size of the foot. This is 

 particularly the fact in respect to the smaller of the outline tracks 

 given on Fig. 2, a ; for the animal by which this was made, had 

 a stride of two feet : nor is this confined to a single specimen ; 

 so that the idea that the animal was running, is not probable. 

 The great disparity between the step in the large specimen (fig. 

 2, b) and the small one (fig. 2, a), has led me to suspect that in the 

 above description I may have embraced two species : but their 

 form coincides too exactly to allow of a separation : and yet the 

 large track shows a stride of only 13 inches, while that of the 

 smaller one is 24 inches. The former is from Turner's Falls in 

 Gill, and the latter from South Hadley. I am more disposed to 

 this opinion, from the fact, that I find another row of tracks on 

 the same slab from South Hadley, that contains fig. 2, a, running 

 in the opposite direction, and about as large as fig. 2, b, yet exhib- 

 iting a stride of 29 inches. See the two rows on Fig. I, a, a, a, 

 a, and b, b, b, b. ... 



The ratio between the length of the foot and the step m this 

 species, (taking the two examples on fig. 1 as our guide ) is 

 *nuch greater than that of any other animal whose footmarks I 

 have found. That ratio is 8 for the smaller track, and 8-3 tor the 

 J arger: that is, the step is eight times larger than the foot. Ap- 

 plying the rule which I have suggested for ascertaining from 

 these numbers the length of this bird's leg / we find t to be 39 



* MS Final Report by the writer on the Geology of Massachusetts, vol. ii, p. 52SJ. 



