PRIMEVAL SALAMANDERS. 73 



FIG. 21. Skull of the Giant Primeval Salamander (Mastodonsaurus), one- 

 sixth natural size. S.Occ., supra-occipital bone ; Ep., epiotic ; P., parietal ; 

 Sq., squamosal ; S.Temp., supra-temporal ; Pt.F., post-frontal ; Pt.Orb., post- 

 orbital ; F., frontal; Pr.F., pre-frontal ; N., nasal; P. MX., pre-maxilla ; 

 Mx.Sup., maxilla; L., lachrymal; Ju., jugal; Q.Ju., quadra to- jugal. On 

 the right side of the skull (left side of Figure) the external sculptured layer 

 of bone is shown, which is omitted on the left in order to show the contour 

 of the individual bones. The large apertures are the eye-holes or orbits ; the 

 smaller shaded apertures in front, the nostrils ; and the smallest of all the 

 holes for the points of the tusks of the lower jaw. The projecting processes 

 at the top of the Figure are the occipital condyles. (After Fraas.) 



