ANCIENT SALAMANDERS 
97 
it to the batrachian type with permanent gills. Both tend to 
show the artificial nature of the arrangement by which, under 
most systems of classification, fishes are separated by a wide gap 
from reptiles and amphibians. 
The Labyrinthodonts ranged through three geological periods 
— the Carboniferous, the Permian, and the Triassic. At the 
time when the coal-forests of Europe and America were flourish- 
ing, they were tenanted by a large number of Labyrinthodonts. 
These, and others of the succeeding Permian period, which may 
conveniently be taken together, have been specially studied by 
such authorities as Professors Huxley and Cope, Dr. Fritsch, 
Fig. 18. — Skull of Archegosaurus. (Permian.) 
Professor Miall, and others. The limits of space will only 
allow us to make a small selection from the numerous forms 
described by them. 
Cricotus is an American genus described by Professor Cope, 
from the Permian strata of Texas. The skull and some of the 
scales belonging to the under surface of the body are shown in 
Fig. 19. The Eryops, of which the skull is shown in the same 
figure, is considered by Professor Seeley to belong to a higher, 
though related group, the Anomodonts (Chap. YII.). The one 
group is much connected with the other, and the question of the 
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