THE TEMPORAL ARCHES OF THE REPTILIA. 



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quadratojugal. The quadratojugal has only a slight union with 

 the jugal. The postfrontal joins by its whole length with the 

 parietal. Now, no one will question but that this arrangement 

 of these bones is the primitive one for the reptilia, and any rear- 

 rangement or readjustment must be a secondary result or spe- 

 cialization. 



Among the higher forms, the nearest approach to this condi- 

 tion is seen in the testudinate skull (Fig. 3), in which the bony 

 roof still remains unpierced ; that is, there is no supra- or latero- 

 temporal fenestra in such forms as Chelone, an undoubted prim- 

 itive type of testudinate skull. The postorbital and postfrontal 



FIG. 14. Cynognathus, after Woodward. 



are not distinct, or one or the other is absent. The prosquamosal 

 has disappeared, or has become fused with some adjacent ele- 

 ment. The quadrat ojugal has become greatly enlarged, sep- 

 arating the jugal from the quadrate, and articulating above with 

 the squamosal that is, it has taken the position of the pro- 

 squamosal in the Pareiasaunts skull. It is assumed that the 

 prosquamosal, if present, is fused with the -squamosal, but I fail 

 to see any conclusive evidence of this ; and it would seem more 

 reasonable that, if the element is really present in the testudinate 

 skull, it is fused with the quadratojugal, which has usurped its 

 place and relations. Indeed the loss of the narrow bone on the 

 outer side of the cotylosaurian skull would leave an arrangement 

 pretty similar to that of Chelone, except that the quadrate is 

 partly uncovered. 



In the posterior part of the skull a vacuity has arisen, or, mor e 



