Amphibia Labyrinthodontia. 



67 



pelvic pair ; the feet pentadactyle. Skull with the temporal region Wall-case, 

 completely roofed over by the post-orbital and supra-temporal No. 11. 

 bones ; with a parietal foramen. Teeth pointed, having a large Table-cases, 

 pulp-cavity and the dentine simple or plicated. Vertebrae amphi- Nos * 22 > 2S * 

 coelous; they may be imperfectly ossified, and a notochordal 

 canal is often present. A bony thoracic buckler on the ventral 

 aspect. Bony scutes frequently present on the ventral aspect 

 of the body. Teeth are generally present on the palatines and 

 vomer and more rarely on the pterygoids. There is generally 

 an ossified sclerotic ring. 



FIG. 88. Frontal aspect ot cranium 

 of Capitosaurus robustus (Meyer); 

 Middle Keuper (Upper Trias), near 

 Stuttgart, Wiirtemberg. Letters as 

 in Fig. 86. (^ nat. size.) 



FIG. 89. Frontal aspect of the cranium 

 of Metoposaurus diagnosticus 

 (Meyer) , Upper Trias, near Stutt- 

 gart. 'Letters as in Fig. 86. ( 

 nat. size.) 



The Labyrinthodonts were frequently of large size; the 

 dentine of the teeth was usually plicated ; the cranial bones were 

 deeply sculptured and usually marked by numerous mucus- 

 canals. 



The Labyrinthodonts range from the Carboniferous to the 

 Trias, and were especially abundant in the Permian epoch. 



One of the largest of these forms is the Mastodonsanrus 

 giganteus (Jaeger), from the Keuper of Wiirtemberg, the skull 

 of which measures a yard in length, and broad in proportion ; 

 the snout is obtuse, the nares are oval and widely separated ; 

 the orbits are oval, but narrow in front, and are some distance 

 in advance of the parietal foramen ($ee Fig'. 86). 



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