THE SKULL OF REPTILES 65 



one the supratemporal or its synonym, the prosquamosal. Yet others 

 both in the past and the present call the outer anterior bone the 

 quadratojugal. The author has given his reasons for believing that 

 the posterior bone is none of these but the tabular instead, the an- 

 terior one the squamosal, the quadratojugal absent. He believes 

 that the posterior is the tabular because it occupies the primitive 

 position of that bone in its relations to the interparietal, paroccipital, 

 squamosal, and quadrate. The supratemporal is the first bone to 

 disappear in the temporal region of the Cotylosauria, and its pres- 

 ence has never been positively determined in the Theromorpha and 

 Therapsida. 



It is quite possible, however, that both the tabular and supra- 

 temporal have disappeared in these reptiles, and that the squamosal 

 has usurped their position and functions; the true supratemporal, 

 however, has no relations with the quadrate as has the bone so called 

 in the skull of the lizards. If so, the bone articulating with it in front 

 and forming the outer boundary of the temporal opening may be the 

 quadratojugal, as was formerly believed and yet is by some. It is 

 a fact, however, that the quadratojugal is a very inconstant bone in 

 all single-arched reptiles otherwise. It is very small in the Thero- 

 morpha, is present in only a very few of the Therapsida as more or 

 less of a vestige, and has wholly disappeared in the Sauropterygia. 

 That it should lose its original position at the lower outer side of 

 the quadrate, to form part of the articular surface for its upper 

 end, seems improbable. Furthermore, in the Ichthyosauria (and 

 ? Saphaeosaurus) there is a distinct bone between it and the temporal 

 opening that must be either the squamosal or supratemporal. There 

 is at present no certain solution of the problem. 



The Skull of the Squamata 



(Figs. 54-59) 



The skull of the Squamata is at once distinguished from that of all 

 other reptiles by the movable, streptostylic quadrate, secondarily 

 more or less fixed in some forms. The exoccipitals and paroccipitals 

 are always fused ; the pterygoids never reach the vomers ; the inter- 

 parietals and either the supratemporals or tabulars, or the quadra- 

 tojugals, according to the identification, are absent. The teeth are 



