[MATTHEW] NEW GENUS OF BATRACHIAN FOOTPRINTS 89 



The fore foot makes a much lighter impression than the hind foot, 

 but the print of the sole seems to be habitually present though often 

 faint. 



The stride and movement of the animal (if we are right in refer- 

 ring a certain series of tracks to this species) were variable, and the 

 species in its hind foot resembles Thcnaropus McNaughtoni, but that 

 species does not show the fifth toe. 



The tracks occur in a fine grained gray sandstone where there are 

 frequent alternations of sandy clay. The weight of the animal has 

 pressed the imprint through several layers of this clay. 



x\SPERIPES FLEXILIS n. Sp. 



PI. I, figs. 3a-c. PI. VI, figs. 3 and 4. 



Stride, 5^ inches (140 mm.). Straddle, 2 inches (50 mm.). Fore 

 foot about 1^ inches (30 mm.) behind the hind foot, and in one example 

 somewhat outside of it. 



Hind foot. Length about 30 mm., width about 25 mm. Five toes 

 mostly directed forward except the fifth digit which is turned outward; 

 the others are progressively shorter inwardly. Sole about 13 mm. long 

 and 20 mm. wide. Angle of digits, I-V=95° ?-110° ; 1-11=40° ?-45°. 

 Fore foot. Length 33 mm., width 25 mm. Three toes, the outer one 

 spreading from the others, turned outward, the other two directed for- 

 ward and inward. Sole length (including heel 20 mm., width, 17 nun.; 

 the heel as in the proceeding species is turned outward. 



The toes in this species show great flexibility, crossing each other 

 or turned in under the sole. The fossil is a cast in fine gray sand of 

 tracks made on a, muddy layer; from the long stride one might think 

 the animal was in rapid motion, but the irregular position of the toes 

 does not agree with this; the tracks may have been made by a narrow 

 long legged quadruped. 



This animal was remarkable for the length of its stride which was 

 nearly three times as great as the straddle; also for the flexibility of its 

 toes the positions of which are unusually varied. 



This species is distinguished from A. avipes by its somewhat larger 

 size, more evenly developed hind foot and by the swelling on the inside 

 of the fore foot. 



