PERMOCARBONIFEROUS AMPHIBIANS AND REPTILES 59 



structure of the skull in air-breathing animals, in part at least, 

 of the mandibles, shoulder and pelvic girdles, wrist, ankle, and 

 digits has been determined almost exclusively from these forms. 



Three very distinct groups or orders of amphibians are known 

 from these deposits, including more than twenty known genera. 

 The first of these groups is represented by small animals of the water 

 which must have existed in enormous numbers. There are places 

 in Texas where the nodules containing their remains, usually 

 nearly complete skeletons, may be obtained hterally by the wagon- 

 load. They resembled so closely in shape, and doubtless also in 

 habits, the Hving Amphiuma means of the southern states, that a 

 picture of that creature will almost serve for a restoration of this, 

 which is known as Lysorophus. Most interesting is the fact that 

 not only did Lysorophus resemble Amphiuma in size, shape, and 

 habits, but it seems to be actually related to it, being the first rep- 

 resentative known of the modern salamander type, not again 

 known in geological history till the beginning of Cretaceous time. 



A second group of very remarkable aquatic amphibians, whose 

 relationships are still in doubt, is represented by Diplocaulus, 

 a creature which reached a length of about three feet, having an ex- 

 traordinary arrow-shaped head, and tiny, feebly ossified limbs of no 

 terrestrial and little aquatic use. It, too, was a purely aquatic 

 animal, whose remains are often found associated with those of 

 the early sharks. A restoration of the skeleton of Diplocaulus 

 will shortly be pubhshed in this Journal by Mr. Douthitt of the 

 University of Chicago. 



The third and most important order of all our Permocar- 

 boniferous amphibians is that known as the TemnospondyH, 

 stegocephahans especially characterized by the divided condition 

 of the vertebrae. They varied greatly in size, and doubtless also 

 in habits, though none known were of upland habit. The most 

 famous of these is Eryops, shown in Fig. i in what I have tried to 

 represent as a characteristic landscape of the period in which they 

 lived. It was an amphibian which reached a length of perhaps 

 eight feet, and had a relatively large, broad, and flat head, no 

 neck, a thickset body, and short, broad, probably webbed feet. 

 The length of its tail is still in dispute, as may be inferred from 



