"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.
The review of the proposed systems of classification has been much facilitated by the discovery, in the University of Chicago, of some notes by the late Dr. George Baur on the "Stegocephali." The notes were not discovered until after the literature had been pretty thoroughly covered, and it was a source of some gratification, on comparing notes with those of Dr. Baur, to find but few omissions. Whether Dr. Baur had ever contemplated a work on the Stegocephala or not I have been unable to learn, but it is certain that he carefully and laboriously went through the literature on the subject and copied by hand the classifications of each author from 1842 to 1895, together with other notes of interest on the structure, distribution, and phylogeny, including many tracings. The classifications given below are taken, in part, from his notes, although all references have been verified with the original sources.
The first attempt to combine in classification the knowledge of the extinct and recent amphibians was made by Johannes Jacob von Tschudi in 1839 ([574]). Previous to that time Goldfuss ([295]) and von Meyer ([418]) had described various species of salamanders and frogs from the Tertiary deposits of Switzerland, and these Tschudi considered in his following classification:
A. Ranæ.
a. Hylæ.
b. Cystignathi.
c. Ranæ.
d. Ceratophrydes.
e. Bombinatores.
f. Bufones.
g. Pipæ.
B. Cœciliæ.
a. Cœciliæ.
C. Salamandrinæ.
a. Pleurodeles.
b. Salamandræ.
c. Tritones.
d. Tritonides.
D. Protoideæ.