514 SIQIQMES, SHORE, SI UIDIBIN IGS, 
palato-vomerine tusks on each side. The whole animal had a 
probable length of about ten feet, the head being disproportion- 
ately large. 
Labyrinthodon from the same horizon as the previous forms 
is, according to Lydekker,a synonym of Mastodonsaurus. It 
was described by Owen from a single tooth and the name was 
founded on the peculiar folding of the dentine. As most all of 
the Labyrinthodontti have the same character the distinction fails ; 
it is as well however to know the genus as the name is a common 
one in the text-books. (See Owens, Odontography, Pl. LXIII. 
Fig. 1, for a picture of the structure of the labyrinthodont tooth.) 
Nyrania from the Permian of Bohemia and SLothriceps and 
Micropholis from the Permian of South Africa are less well known 
foreign genera. Certain imperfectly preserved remains have 
been collected from the rocks of the Newark system of Penn- 
sylvania and North Carolina. Lwpelor is the name of the small 
form from Pennsylvania, and Pariostergus and Dictyocephalus from 
the Carolina region. Quite recently a tooth has been described 
from the Upper Carboniferous of Kansas, and referred to the 
genus Mastodonsaurus,; if the determination is correct this indi- 
cates a rather peculiar distribution for the genus as it is 
unknown from the English deposits, though quite common on 
the continent. 
Below is a summarized list of the most important forms of 
the Labyrinthodontia with their geological range and habitat so 
far as known. 
LABYRINTHODONTIA. 
Branchtiosaurta. 
Branchiosaurus, Rothliegende, Germany. 
Melanerpeton, Apateon and Pelosaurus, Rothliegende, Germany. 
Protriton, Rothliegende, France. 
Amphtbamus and Pelion, Carboniferous, Ohio. 
Microsauria. 
flylonomus and [Hylerpeton, Carboniferous, Nova Scotia. 
Tuditanus, Osteocephalis and Colosteus, Carboniferous, Ohio. 
Flyoplesion and Microbrachis, Carboniferous, Bohemia. 
Lepterpeton and Keraterpeton, Carboniferous, Ireland. 
