STEGOCEPHALIA. 



Sub-Order 1. Branchiosauria. 



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One group of Stegocephalia from the Upper Carboniferous 

 and Permian comprises very small salamander-shaped animals, 

 with a long but broad tail. These are named BRANCHIO- 

 SAURIA from the presence of functional gill-arches in immature 

 individuals, as indicated by the regular series of minute 

 denticles which were originally arranged upon them. The 

 teeth are simple hollow cones, not with folded walls ; and those 

 of the palate are relatively small or may be entirely wanting. 

 The occipital region of the chondrocranium is not ossified. The 

 notochord seems to have been completely persistent, thickening 

 slightly in the middle of the barrel-shaped vertebrae, which are 



FIG. 83. 



Diagrams of Branchiosaurian (1, 2) and Microsaurian (3, 4, 5) Vertebra, much 

 enlarged. 1. Vertebra of Branchiosaurus, lateral aspect. 2. The same, 

 end view. 3. Vertebra of Hyloplesion, inferior aspect. 4. The same, lateral 

 aspect. 5. The same, end view, c, notochordal canal ; he., hypocentrum ; 

 71, neural canal ; pi., transverse process. (After Credner.) 



described as of the unique construction represented in fig. 

 83 i, 2. A pair of delicate hypocentra or intercentra (he.) 

 encircles the lower half of the notochord (c.) and forms part of 

 the transverse process on each side for the support of the rib ; 

 while the neural arch itself, in the absence of pleurocentra, 

 extends downwards to cover the superior lateral portion of the 

 notochord, and also enters into the formation of the transverse 

 processes (pi.). The ribs are single-headed, very short and 

 stout. The sternum and pubic cartilages are not ossified ; and 

 no trace of ossifications has been observed in the carpus or 

 tarsus. 



Braachiosaurus (figs. 82, 83 i, s, 84 A, 85 A). This is perhaps the best- 

 known genus of Stegocephalia, being represented by innumerable specimens 

 in all stages of growth from the Lower Permian of Saxony, Bohemia, and 



