SKULL — REPTILES 



155 



are vomers, palatines, pterygoids, transverse and parasphenoid, with 

 a septomaxillary in the nasal capsule, resting on the nasal septum 

 and lateral wall of the labyrinth; it is apparently the same as the bone 

 in Amphibia, but is deeper in the capsule. Parietals and frontals 

 are fused in pairs, except in some of the more aberrant genera. When 

 the parietals form the whole of the roof of the cranial cavity, the 

 parietal foramen is between them, but when the frontals enter the 

 roof, the foramen is between the four bones. Occasionally, as in 

 Anniella, the foramen is lacking. The premaxillae are fused and send 



Fig. 164. — Cranium of Varanus. bo, basioccipital; bs, basisphenoid; eo, exoccipital; 

 ep, epipterygoid; /, frontal; I, lacrimal; m, maxilla; n, nasal; p, parietal; pi, palatine; 

 ptn, premaxilla; po, prootic; pof, postfrontal; prf, prefrontal; pt, pterygoid; q, quadrate; 

 qj, quadratojugal; so, supraoccipital; sq, squamosal; t, transversum; v, vomer; z, 

 zygomatic. 



a process back to the nasals. As in most Squamata, there is a single 

 postfrontal-squamosal arcade (zygomatic also in Chameleo, figure 165) 

 bounding the temporal fossa laterally while a postorbital arcade of 

 zygomatic and postorbital separates orbit and temporal fossa, but is 

 more or less reduced in Varanus, Gecko, etc. 



The most constant vacuities in the cranial floor are one lateral 

 to each vomer, and another medial, bounded by palatines and 

 pterygoids. Pterygoid and basisphenoid have a basipterygoid 

 articulation. The parasphenoid is paired in origin in Lacerta, the 



