506 STUDIES FOR STUDENTS 
the teeth as in the more advanced forms. The bones were 
largely cartilaginous, the tarsus and carpus and the bones of the 
occipital portion of the skull entirely so. The ventral surface 
of the body was protected by a large number of dermal scutes. 
Most of these forms are known from the Rothliegende 
of Germany, but specimens have been found from the same 
horizon and from the Upper Carboniferous of France and Ohio ; 
from the German region a very large number of forms have been 
taken in the most excellent state of preservation so that it has 
been possible to study not only the adult forms, but the young 
stages as well and to make out the various steps in the meta- 
morphosis of the individual. Credner studied a large series of 
forms from about 30™™ to 120™™, and made out all the stages of 
development, the growth of the external giils, their loss, and 
the assumption of the adult form. 
Lranchiosaurus is the best known genus of the suborder 
and a description ot it may serve as an illustration of the whole 
group. The head was comparatively large and rounded in 
front; the edges of both jaws were lined with numerous small, 
conical teeth; the skull was completely roofed by dermal bones, 
and the surface of these bones show a very strong sculpture. 
The condition of the vertebra, the carpus and tarsus, and the 
bones of the occipital region was as already described; the 
limb bones were cartilaginous at the extremities. The eyes 
were rather large and were protected by bony plates developed 
in the sclerotic coat, the ‘‘sclerotic plates.” The whole animal 
must have presented much the same appearance as one of the 
modern salamanders and had, probably, much the same habits, 
never going any great distance from the water. 
Melanerpeton, Apatcon, and Pelosaurus from the same locality 
and horizon as the branchiosaurus, were very similar in appear- 
ance, differing only in minor skeletal characters. 
Protriton is a form described from the Rothliegende of Autun, 
in France, and is regarded by some as identical with the early 
stage of Branchtosaurus as it has the external gills and other 
characters of the larval forms of that genus. 
