190 THE ANATOMY OF VERTEBUATED ANIMALS. 



end ot" one of these processes (in which a small separate ^tero- 

 tia ossification sometimes appears), and is usually movable. 

 The parietal bones do not unite suturally with the occipital 

 segment of the skull, or with the prootic bones, but are con- 

 nected with them only by fibrous tissue. And as the presphe^ 

 noidal region remains unossified, or incompletely ossified, it 

 follows that the fronto-parietal portion of the skull is, in most 

 Lizards, slightl}' movable upon the oocipito-sphenoidal part. 



Each parietal bone is prolonged backward into a process 

 which articulates with the upper part of the parotic prolonga- 

 tion of the skull ; and to the outer side of the posterior ex- 

 tremity of the parietal process the squamosal is attached. The 

 squamosal may be continued forward to the post-frontal, which 

 is sometimes subdivided into two. The post-frontal may unite 

 below with the jugal, and thus bound the orbit. Only in 

 Spheiiodon, among recant Lizards, is the jugal connected with 

 the distal end of the quadrate by bone. As a general rule, the 

 quadrato-jugal is represented only by a ligament. 



In consequence of the structure which has been described, 

 the posterior region of the ordinary Lacertilian skull presents 

 a number of distinct fossae in the dry state. A supra-temporal 

 fossa lies between the parietal, the post-frontal, and the squa- 

 mosal, on the upper face of the skull ; a post-temporal, between 

 the parietal, the occipital, and the parotic apophysis on the 

 posterior face ; a lateral-temporal, between the squamosal and 

 post-frontal above, the jugal and quadrate in front and behind, 

 and the quadrato-jugal ligament below. 



The palatine and pterygoid bones are firmly connected both 

 with the facial bones, and with the floor of the skull. Thus 

 the basisphenoid gives off two basipterygoid processes, the 

 outer ends of which articulate with the inner sides of the ptery- 

 goid. The posterior ends of the pterygoids are usually con- 

 nected with the inner surfaces of the distal ends of the quad- 

 rate bones. Their anterior ends are firmly united with the 

 palatines; and, from the junction of the two, a,'transverse 

 bone (Fig. 70, Tr) usually passes, to unite the palatine and 

 pterygoid with the maxilla. 



The anterior ends of the palatines unite with the maxillae 

 and the vomers ; but, in existing LaceHilia, they do not meet 

 one another, or come into contact with the basisphenoid or 

 presphenoid in the middle line. The palatine apertures of the 

 nostrils are placed between the palatine bones, on the outer 

 side, and the vomer, on the inner. In only a few Lacertilia 

 do the palatine bones send down processes which bend tow 



