STEGOCEPHALI. 315 



of which are amphibian and others reptilian. But whatever 

 view be taken on this point, it is clear that none of them can be 

 regarded as bridging the gulf between the piscine and terrestrial 

 type, for not only do they all present fairly speciahsed skeletal 

 features, but in all in which the extremities are known the 

 pentadactyle type of skeleton is fully developed. 



Sub-order 1. BRANCHIOSAURI. Small salamander-like animals, with 

 well developed gill arches in wliat are supposed to be immature specimens. 

 Occipital region of skull unossified. Carpus and tarsus cartilaginous. 

 Ventral scales thin and in rows. Upper Carboniferous and Permian. 

 Branchiosaurus Fritsch {Profriton, Pleuronura), Lower Permian of Saxony, 

 Bohemia and France (Fig. 176) ; Pelosaurus Credner ; Melatterpeton 

 Fritsch ; Dawaonia Fritsch ; Amphibamus Cope ; Pelion Wyman ; 

 Urocordylus Huxley and Wright. 



Sub-order 2. AISTOPODA. Body long, snake-like without limbs or 

 pectoral girdle ; vertebrae amphicoelous. Upper Carboniferous, Lower 

 Permian. Dolichosoma Huxley, Ophiderpelon Huxley. 



Sub-order 3. LABYRINTHODONTIA. The dentine of the teeth is much 

 folded, ventral armour is usually present. From the Lower Carboniferous 

 to the Tria^. Archegosaurus H. v. Meyer, with ventral armour, 4 fingers, 

 5 toes, Lower Permian ; Sparagmites Fritsch ; Chelidosuurus Fritsch ; 

 Actinodon Gaudry, etc. Mastodonsaurus Jaeger, the largest Labyrintho- 

 dont, the skull may attain a length of 1.25 m., Trias ; Trimatosaurua 

 Braun ; Labyrinthodon Owen, Keuper. Labyrinthodonts are described 

 from the Trias of S. Africa and of New South Wales. Footprints which 

 are supposed to have been made by Labyrinthodonts are found in the 

 Lower and New Red Sandstone of Europe, Africa and America. 

 Such footprints usually show five fingers and five toes, which is incon- 

 sistent with this view as no Labyrinthodont is known to have 5 fingers. 



The MiCROSATJBiA from the Upper Carbonifei'ous and Lower Permian 

 with Hyloplesion, Petrobates, Keraterpcton, Lepterpetoti, Seeleya etc., 

 are usually placed with the Stegocephali. 



