THE FOSSIL FOOTMARKS OF THE UNITED STATES. 171 



Species 2. Brontozoum Sillimanium. (PI. III. Fig. 2.) 



Ornithoidichnites tuberosus in part, and O. cuneatus, of Mass. 

 Geol. Report, Plate 37, fig. 21, and Plate 38, fig. 22. 



Ornithoidichnites Sillimani^ Transactions of Association of Amer. 

 Geo]., p. 256. 



Nos. 44, 47-52, 55, 56, 90, 126, 138, 144, 149, 173, 185, 186, 

 206, 209, 234, in Cabinet. 



Divarication of the lateral toes, 30° to 40° ; of the inner and 

 middle toes, 20° to 30° ; of the outer and middle toes, 10° to 20°. 

 Length of the middle toe, 6 inches ; of the inner toe, 4.4 inches ; 

 of the outer toe, 5.5 inches ; of the foot, 8 inches ; of the step, 

 18 to 20 inches ; of the claw, 1 inch. Distance between the 

 tips of the lateral toes, 5 inches ; between the tips of the inner 

 and middle toes, 4 inches ; between the tips of the outer and middle 

 toes, 3.5 inches. Projection of the middle toe beyond the lateral 

 ones, 3 inches. Width of the toes, 1 to 1.9 inch. Length of the 

 proximal phalanx of the inner toe, 0.9 to 1 .6 inch ; of the penulti- 

 mate and ultimate phalanges united, 0.8 to 1.3 inch; of the prox- 

 imal phalanx of the middle toe, 0.9 to 1.5 inch; of the second, 1 to 



1.6 inch ; of the penultimate and ultimate phalanges united, 0.8 to 



1.7 inch ; of the proximal phalanx of the outer toe, 0.7 to 0.9 inch ; 

 of the second phalanx, 0,7 to 0.8 inch; of the third, 0.6 to 1 inch; 

 of the penultimate and ultimate phalanges united, 0.8 to 1.5 inch. 

 Extremity of the tarso-metatarsal bone with two condyles for artic- 

 ulation with the toes. Axis of the foot nearly coincident with the 

 line of direction. Claws nearly straight, and only slightly deflexed 

 from the axis of the toes. Tracks shown, of the natural size, on 

 Plate 3, fig. 2, which exhibits also an impression of the double- 

 headed extremity of the tarso-metatarsal bone ; copied from a speci- 

 men from South Hadley. 



