MARTIN: A GIG/ .,TIC AMPHIBIAX. US. 



EXPLANATION OF PLATE II. 



Photograph of the east bank of the W'.'k^rusa creek at Dightman's crossing, 

 five miles southeast of Lawrence, Kan. howing the relation of the heavily 

 bedded sandstone, in which the ampi >ian footprints were found, to the 

 Weston shales which outcrop immelui ly at the edge of the water. The 

 ravine in the center of the picture hs..> ;a depth from the surface of twenty 

 feet, and in this depression, on the ledge indicated at the point of the arrow, 

 was found the series of footprints shown in the plate. This ledge at the 

 position of the first track lies fourteen feet above the creek, but the stratum 

 rises three feet between the first and the second impressions, between which 

 there is an eroded interval of twelve feet. A further inclination of the 

 stratum is indicated in the fact that /here is a rise of four feet between the 

 second and the last impressions, a "'istance of twenty-seven feet. The ledge 

 on which the impressions were fou^rd is continued into the sandstone cUff 

 immediately above the star (*). 



8 — Science Bui. — 3728 



