RHTNCHOCEPHALIA. 



331 



The dentition is acrodont, and the teeth are fused with the 

 subjacent bone. The premaxillary teeth, and the dowmwardly 

 curved premaxillae with which they are fused, have the appear- 

 ance, especially when worn down, of a pair of rodent -like incisors. 

 There is a row of small triangular teeth on the maxilla and 

 another on the palatine. The single row of mandibular teeth 



VI * Ptf Po^ ^* 



Fia. 182.— Sphenodon punctaius, skull A from the side B from above, C from below, D from 

 behind (after Gunther, from Zittel). 4 orbit ; Any angular ; art articular; Bo basi- 

 occipital ; Ch internal nares ; d dentary ; Exo exoccipital ; Fr frontal ; Jti jugal ; E sur- 

 angular ; Mx maxilla ; N external nares ; Na nasal ; Opo opisthotic ; Pa parietal ; PI 

 palatine ; Pmx premaxilla ; Por postorbital ; Pr, prefrontal : Pt pterygoid ; Ptf postfrontal ; 

 Qu quadrate ; Qu Ju quadrato-jugal ; S superior temporal fossa ; Sq squamosal ; So supra- 

 occipital ; Vo vomer. 



bite between these two rows in the upper jaw. In some young 

 specimens there are a few small teeth on the vomers. The 

 pterygoids are edentulous. ^ 



There is a T-shaped interclavicle and a clavicle, and the cora- 

 coid is without fenestrae. The humerus has an entepicondylar 

 as well as an ectepicondylar foramen. The carpus has ten 

 separate bones. The pelvis is somewhat lacertilian though the 



