198 AN ATTEMPT TO DESCRIBE THE ANIMALS THAT MADE 



ture of the outer toe, 0.3 inch. Foot plantigrade. Toes very slen- 

 der. Track shown, of the natural size, on Plate 9, fig. 1. 



Localities. — Chicopee Falls, in the bed of the river ; and at a 

 quarry one mile south of Cabotville. 



Remark. — I have not met with a sufficient number of these 

 tracks in place to be sure that they were not made by a quadruped. 



Genus VIII. PLECTROPUS. 



Heel elongated, apparently extending to the tarsal joint, quite 

 narrow, making an impression as deep as the toes with its anterior 

 part. Fourth toe proceeding at right angles from the heel behind 

 the roots of the toes, resembling the spur on some of the galli- 

 naceous birds. 



Species 1. Plectropus minitans. (PI. IX. Figs. 2, 3.) 



Sauroidichniies minitans, Mass. Geol. Report, Plate 33, fig. 11. 



Nos. 17-23, 153, in Cabinet. 



Divarication of the lateral toes, 87° to 93° ; of the inner and 

 middle toes, 37° to 42° ; of the middle and outer toes, 45° to 60° ; 

 of the middle and hind toes, 90° to 110°. Length of the middle 

 toe, 2.5 to 3.8 inches ; of the inner toe, 1.7 to 2.6 inches ; of the 

 outer toe, 1.8 to 2.5 inches; of the hind toe, 0.9 inch ; of the heel, 

 1 to 2 inches; of the foot, 3.5 to 6 inches ; of the step, 15 to 17 

 inches. Width of the heel, 0.4 to 0.5 inch ; of the foot at the roots 

 of the front toes, 0.4 inch. Distance between the tips of the lateral 

 toes, 2.7 to 3.7 inches; between the inner and middle toes, 1.6 to 

 2.6 inches ; between the outer and middle toes, 2.4 to 2.9 inches ; 

 between the middle and hind toes, 3.3 to 4.8 inches. Length of the 

 middle toe beyond the rest, 1.5 to 2 inches. Versed sine of the in- 

 ward curvature of the middle toe, 0.15 inch ; of the outward curva- 



