502 SINGERS IAI SA GIOIEIN IOS) 
Class, AMPHIBIA. 
Order, Labyrinthodontia. 
. Suborder, Branchiosauria. 
Microsauria. 
Atstopoda. 
Labyrinthodonta vera. 
a, Embolerimt. 
b, Rachittomtz. 
c, Labyrinthodontz. 
Order, Coeczlia. 
Caudata ( Urodela). 
Suborder, Salamandrina. 
Icthyotdea. 
Order, Ecaudata (Anura). 
Suborder, Arczfera. 
Firmisterna. 
A glossa. 
It is with the first of these orders that the student of palaon- 
tology is the most concerned, as they were the predominant 
forms of life during the Carboniferous time and even during the 
first part of the Mesozoic. The other orders did not assume 
any importance before the beginning of the Tertiary, and only 
one of them, the Caudata, appeared as early as the Cretaceous. 
The earliest trace of amphibians is found in the Devonian 
rocks of Warren county, in Pennsylvania, and consists of tracks 
of some large labyrinthodont that Marsh has called Zhznopus 
antiquus (Am. Jour. Sct., 1896). No other trace of the Amphibia 
has been found in rocks earlier than the Carboniferous, but with 
the appearance of that time a large number of forms were devel- 
oped that in the variety of their forms and the degree of their 
specializations rivaled the development of the reptiles of later 
times. To this large group of semi-aquatic forms Huxley gave 
the name Ladyrinthodonta in 1863; five years later Cope gave 
the name Séegocephali to the same group. The latter name is 
used the most commonly in this country. 
In external appearance the Labyrinthodontia were very simi- 
lar to the existing tailed amphibians, the body was long in some 
cases and in others more stout and heavier; the skin was naked, 
