8o 



STEGOCEPHALI 



iirticulars, angulars, aud splenials. The dentaries and apparently 

 sometimes the splenials, the palatines, maxillae, and vomers carry 

 teeth. The eyes possess a ring of sclerotic bones. 



Order I. STEGOCEPHALI LEPOSPONDYLI. 



Vertebrae pseudocentrous. 



Sub-Order 1. Branchiosauri. — The young- had several pairs 

 of gill-arches, which, to judge from their size and from the 



F[(! 



12. — A, Dorsal aud B, ventral views of the cranium of Branch iosaurus salaman- 

 droides, x about 4. (After Fritscli.) C, Posterior view of tlie cranium of Tremato- 

 saurus, x about h. (After Fraas.) Jh; Brancliial arches ; V, condyle ; Jiji, epiotic ; 

 F, frontal ; J, jugal ; L.O, lateral occipital ; M, maxillarj- ; iN', uasal ; i\'o, nostril; 

 Pa, parietal ; PI, palatine ; Pm, premaxillary ; P.o, postorbital ; Pr.f, jjre frontal ; 

 Ps, parasphenoid ; Pt, pterygoid ; Ptf, postfroiital ; (,>, quadrate ; (,),/, quadrato-jugal ; 

 S.o, snpraoccipital ; Sq, squamosal ; St, snpratemporal ; V, vomer. 



fact that they are beset with numerous nodules, denticles, or 

 irregular little processes like gill-rakers — seem to have been 

 exposed to the surface and to have carried gills. In the adult 

 the arches and gills seem to be absent. 



One of the commonest genera is Branchiosniinis, including 

 Protritoit. B. salamandroides of the Lower Eed Sandstone of 

 Europe is known in every stage, from larvae of 16 mm. to the 

 full grown animal of 64 mm. in length. The whole body was 



