182 



AMPHIBIA. 



were of comparatively small size ; but some, sucli as Barpli- 

 etes and Anthracosaums (fig. 544), must have attained 

 gigantic dimensions. All the above - mentioned genera 

 seem to have j)ossessed well-ossified vertebrae, with, mostly. 



Fig. 544. — Upper surface of the skull ot Anthracosaurtis Bnsselli, one-sixth of the 

 natural size. Coal-measures. (After Atthey.) 



well-developed limbs, the form of the body being mostly 

 salamandriform, but sometimes fish-like, or serpentiform. 

 Ophiderpeton, however, is beheved to have been devoid of 

 limbs. 



In the Permian rocks, a few remains of Labyrinthodonts 

 have been discovered, the genus Zygosaurus being peculiar to 

 this period. 



In the Triassic rocks the remains of Labyrinthodonts are 

 abundant, the most important genus being Labyrintliodon or 

 Mastodonsaurns (fig. 543). This genus is known mainly by 

 footprints and by crania ; and the size attained by some 

 species must have been colossal. No remains of this order 

 have hitherto been discovered in rocks younger than the 

 Trias, with the exception of the Liassic Rhinosaurus, and the 

 doubtfully Jurassic Brachyops. The absence of examples of 



