1892.1 ^^* [Cope. 



undivided parietal. The supratemporal is accompanied for a short distance 

 above the quadrate by tlie ascending process of the paroccipital. The pi- 

 neal foramen is present in theCiiamieleonidne, Agamid;c, Iguanidee, Anoli- 

 dee, XenosauridiB, Anguidse. Lacertidre, Varanidaj and Scincida}. It is 

 wanting in the Helodermidaj, Eublepharidse, Tiida?, Anniellidoe and in the 

 Amphisbajnia. It perforates the parietal bone clear of all sutures in most 

 of the families, but it is near to or on the frontoparietal suture in Iguani- 

 die and Anolidse, and is in tlie frontal in Dipsosaurus and the Chamajleon- 

 idae. The occipital condyle is compound, consisting of portions of the 

 exoccipitals and basioccipital. In many genera these segments become so 

 thoroughly coossified at maturity as to be undistinguisliable. In some of 

 the Gecconidse (as Gecco, Uroplates) the occipital segment is so reduced 

 as to give the appearance of two condyles. In the Amphisbsenia the 

 cond3'le is transverse and concave at the center, leaving the lateral por- 

 tions prominent. 



The postorbital bone when present sends a process posteriorly to the 

 supratemporal, forming the supratemporal arch. In the genera without 

 this arch the postorbital may be wanting, as in Heloderma, or be rudi- 

 mental as in Anniella. In the genera whose degeneration is advanced, 

 the supratemporal bone is appressed to the parietal, enclosing no foramen 

 supratemporale, as in Feylinia. In limbless genera of Anguidae the su- 

 pratemporal touches the parietal anterior to the paroccipital, thus redu- 

 cing the supratemporal foramen. This occurs also in Gerrlionotus, 

 Celestus, Xenosaurus and Xantusiidse. In Heloderma the supratemporal 

 is a rudiment on the external side of the base of the paroccipital. 



The remarkable upward production of the supratemporal in Chamaeleon 

 has been mentioned. Here this process takes the place of the parieto- 

 quadrale arch. The exoccipitals are produced laterally, each embracing, 

 with the petrosal in front, the small paroccipital. Tliis sustains the 

 superior extremity of the quadrate. In the snake-like genera, as Fey- 

 linia, Anniella and the Amphisbasuia, this lateral elongation does not 

 exist. Tlie exoccipital is scale-like, and the quadrate is sessile on the side 

 of the skull. The quadrate is generally convex at the upper part of its 

 anterior face, and its external anterior border is produced outwards so as 

 to embrace a longitudinal concavity or conch, with the vertical mass or 

 column of the bone. This column is itself more or less concave, its 

 upper extremity being produced a little backwards. In the Iguanida; 

 there is another concavity, internal to the column, similar to the external. 

 This is much narrowed in the majority of the families, and in the Varani- 

 doe and Helodermida}, and in Phrynosoma, Eul)lapliaris, and Celestus it 

 is wanting. In Chamajleon, Anniella and the Amphisbienia there is no 

 external conch, the quadrate being simply a rod ; while in Feylinia it is 

 flattened in an anteroposterior plane. The mandibular articulation is 

 more or less bilobate in all except Varanus, where it is plane. In Gecco 

 the bilobation is strongly marked, as in the Permian Tlieriodonta. The 

 pterygoid bones extend forwards from the quadrates, with which they are 



