THE FOSSIL FOOTMARKS OF THE UNITED STATES. 233 



of its characters, I leave it with the batrachian tribe, on the ground 

 of general analogies only. 



Group VII. LACERTILIANS ? 



Quadrupedal ; fore feet much the smaller. Toes varying from 

 three to five. Heel very long. 



Genus XVIII. MACROPTERNA. 



Hind feet four-toed ; fore feet three to four-toed. Heel long, 

 especially upon the hind feet. Fore feet usually digitigrade, and 

 much smaller than the hind ones. Hind feet usually plantigrade. 



Species 1. Macropterna rhynchosauroidea. (PI. XV. Fig. 9.) 



Ornithoidichniies Rogersi, Trans. Am. Geol. Assoc, Plate 11, 

 fig. 7. 



Ormthoidichnites minimus, in part, Mass. Geol. Report, Plate 45, 

 fig. 41, and Plate 42, fig. 30. 



Nos. 77, 105, 107 - 110, 120, 148, 184, 233, in Cabinet. 



Hind feet. — Tetradactylous, leptodactylous. Divarication of 

 the toes, excluding the short one behind, 80° ; of the inner and 

 middle toes, 30° ; of the middle and outer toes, 50°. Length of 

 the middle toe, 0.7 inch ; of the inner toe, 0.45 inch ; of the outer 

 toe, 0.5 inch ; of the fourth or hind toe, 0.25 (?) inch ; of the foot, 

 1.8 inch; of the step, 3.8 to 5.5 inches; of the heel, 1.2 inch. 

 Width of do., which is uniform throughout, 0.15 inch. Angle 

 made by the axis of the foot with the line of direction, 10° to 50°. 

 Distance of the end of the heel from that line, to 1 inch. Po- 

 sition of the axis of the foot in successive steps, nearly parallel. 

 Distance from tip to tip of the lateral front toes, 0.75 inch ; from 

 31 



