"So far as at present known, land vertebrate life began in the Carboniferous age, no footprints of other remains of this kind having been detected below the Subcarboniferous. That such remains will eventually be found in the Devonian, there can be no reasonable doubt, and perhaps even in the Silurian, if the land surfaces then existing can be explored." This last statement of Marsh's was, of course, partly demonstrated by the discovery of footprints in the Devonian rocks of Pennsylvania, which he described in 1896 as _Thinopus antiquus_. The footprints of _Dromopus agilis_ Marsh which are preserved in obverse in the University of Kansas Museum are of considerably greater length than those described by Professor Marsh. The measurements of one of the larger impressions are appended. There appear to be series of footprints of two different animals preserved on the large slab (5 by 7 feet), but their nature is essentially the same. Measurements of Large Footprint. mm. Greatest length 200 Greatest width 90 Length of longest toe 120 Length of shortest toe 65 Width across heel 50 The slab is No. 5 of the University of Kansas Museum of Natural History, collected in 1873 by Professor B. F. Mudge at Osage, Kansas, and presented by him to the museum in 1875. The following list of Carboniferous amphibian (?) footprints is compiled from Hay's Catalogue of Fossil Vertebrates of North America. It is given here for the sake of completeness. Three types of amphibian footprints are described in the body of this work and they constitute the kind of material which an ichnologist has for the basis of his conclusions. The material is not very satisfactory for the morphologist, though much can be determined as to the foot structure.