MARTIN: A GIGANTIC AMPHIBIAN. 109 



in the sandstone that it looks as if an elephant had recently waded 

 through. A curious consistency of the sandy shale is indicated in 

 the well-preserved indications of foot structure of Onychopus gigas 

 as he trailed through the sandy mud many millions of years ago. 

 It is extremely interesting to note the change in elevation between 

 track one and track nine. While this may be due to the dip of the 

 strata, it may also indicate the shelving bank of a Coal Measures 

 stream which has again been exposed by the gradual erosion of the 

 present Wakarusa creek. 



BIBLIOGRAPHY. 



1. Marsh, 0. C. 1894. Footprints of Vertebrates in the Coal Measures of 



Kansas. Amer. J. Sci. XLVIII, p. 83. (Plate 2, fig. 5.) 



2. MooDiE, Roy L. 1916. The Coal Measures Amphibia of North America. 



Carnegie Institute of Washington. Publ. 238, p. 201. 



3. Lull, R. S. 1920. An L^pper Carboniferous Footprint from Attleboro, 



Mass. Amer. J. Sci. L, p. 234. 



4. Hitchcock, Edward. 1858. Ichnologj^ of New England, Boston. 



5. MooRE, R. C. 1920. Oil and Gas Resources of Kansas. Kans. Geol. Surv. 



Bull. No. 6, part II, page 40. (Geology of Kansas.) 



