516 SIM OVEIS IROIR SINGIDIEINIES 
was about twice the size of the front foot, and there were five 
digits on both. The same form is known from the Triass of 
Cheshire in England. 
It is altogether probable that many of these tracks belong 
to forms already described from parts of the skeleton but until 
some one shall be so fortunate as to discover the skeleton and 
the tracks together it will be impossible to detect the synonymy. 
It has been suggested that the tracks referred to as Chetrosaurus 
belong either to Capitosaurus or to Trematosaurus. 
The whole of the order Labyrithodontia dies out in the Trias- 
sic but the degree of specialization to which the members of the 
order attained bears ample witness to the important part they 
played in the fauna of the Carboniferous and the first part of 
the Mesozoic. Only by the demands of a most severe struggle 
for existence could there have arisen within the limits of a single 
order the necessity for the great divergence of forms that we 
find among the Labyrinthodontia. The wide distribution of the 
forms also bears witness to their prominence, forms being 
known from the East Indies, South Africa, Europe, England, 
and North America. 
The remaining orders of the amphibians are unknown before 
the Cretaceous. 
The Caudata (Urodela) are lizard-like, tailed animals with a 
naked skin and with or without persistent external gills. The 
skull lacks certain of the bones found in the posterior part of 
the skull of the Ladyrinthodontia, as the supratemporal, supra- 
occipital, and the postorbital. The vertebrz are complete in a 
single piece. There are two suborders of the Cuudata, the 
Ichthyoidea, in which the vertebre are biconcave, and the Sa/a- 
mandrina, in which they are opisthocoelus or concave behind and 
convex in front. The common Sven, Proteus, and Menobranchus 
are living representatives of this order. Among the fossil forms 
perhaps the most interesting is the Andrias from the fresh water 
Miocene of CEningen. This form was described as early as 
1726 by Scheuchzer, who considered the imperfect skeleton 
which he had as the remains of an antediluvian man, and gave 
