"Twenty-two footprints made by one animal walking in a straight course were collected in a slab. They give the impression of having been made by a bipedal animal for part of the distance, but after the fourth print of the right foot impressions of the forefeet appear. The hindfeet had 5 digits, the middle digit being longest and the 2 inside of it being only slightly shorter and lying close together. Their outer ends were slender and flexible and usually curved inward toward the middle toe. The 2 outer digits formed wide angles with the middle one and were shorter than the inner ones. The second toe was webbed to within 8 mm. of the tip, the third toe to within 23 mm. of the tip. The impression of the web is well preserved in only one impression of the hindfoot. "The forefeet had 4 digits. The 3 inner digits were subequal in length, the 2 inner being more flexible and incurved near the ends. The outer digit is two-thirds as long as the second. The webbing extends about half the length of the digits. The heel impression is broader than that of the hindfoot. "Measurements of _Dromopus aduncus_ Branson. Tip of toe to tip of toe in first prints 21 cm. After appearance of forefeet the impressions are the following distances apart: 165 mm., 40 mm., 85 mm., 70 mm., 80 mm., 40 mm., 150 mm., then back to 20 and 21 cm. mm. Length of hindfeet 60 Width of hindfeet 20 to 25 Length of forefeet 45" CHAPTER VI. A HISTORY OF THE CLASSIFICATION OF THE AMPHIBIA, WITH ESPECIAL REFERENCE TO THE SPECIES FROM THE COAL MEASURES. It has been necessary, in the course of the present study, to review thoroughly the classifications which have been proposed for the group. A classification of some sort is necessary for the proper grouping of the species which have been recovered from the Coal Measures deposits of this continent, and my reason for publishing this relatively dry material is that the classifications formerly proposed (469), as well as the one here given, may have a proper historical background.