the IloinoJogies of the LizarcVs Skull. 87 



of Thcrapsids given above will show that it is certain tliat 

 the single temporal bone of Sphenodon is really a squamosal, 

 as, except for the difl'erence due to the presence of a single 

 temporal fussa in one and two in the other type, the relations 

 of the two bones are identical. 



The quadrato jugal is applied to the outer side of the 

 quadrate, separated from it largely by the foramen quadrati ; 

 its anterior border is in connection with the squamosal, and 

 a small process runs forward within and below the jugal. 



In the lizards, except where lost by reduction, there are 

 two elements in the temporal region. The homologies and 

 names of these bones have been very much disputed. 



The inner bone has been called : — mastoidien, by Cuvier ; 

 mastoid, by Owen ; squamosum, by Gegeubauer, Baur, and 

 Gaupp ; supra-temporal by Parker, Huxley, Cope, and 

 Bouleuger ; and tabular, by Williston aud Broom, 



The outer bone has been called: — temporal, by Cuvier; 

 quadrato-jugal, by Owen, Gegenbaur, and Baur: squamosum, 

 by Parker, Huxley, Cope, Boulenger, Williston, and Broom ; 

 paraquadrate, by Gaupp. 



These lists make no pretence to be complete, or even to 

 give the changes of opinion of individual authorities, but 

 give some idea of the conflict of opinion. 



The inner bone has the following relations : — 



It forms part of the border of the temporal fossa, sending 

 a process forward along the front of the parietal. The body 

 of the bone forms a small cap on the head of the quadrate ; 

 above aud within this the bone has a powerful articulation 

 with the end of the paroccipital, and sends a process forward 

 along its front face which in Mosasaurs penetrates between 

 the pro-otic aud paroccipital nearly to tbe labyrinth region. 

 The outer face of the bone is covered by the lateral temporal 

 element. 



It will be seen that this bone has exactly the same relations 

 to the quadrate, paroccii)ital, and parietal that the squamosal 

 of Sphenodon or a Thesapsid has, a fact which establishes a 

 strong presumption that it is really a squamosal. If it is a 

 squamosal, the outer bone must be a quadrato-jugal, for no 

 other bone ever lies outside the squamosal ■^. 



The lateral bone in Uromasiix (fig. 1 B, Qu.J.) has the 

 following relations : — It covers a good deal of the outer 



* Except, perhaps, in Ichthijosatirns. 



