CROrODILIANS, LIZARDS, AND SNAKES. 185 



tbe supratemporal touches the parietal anterior to the paroccipital, thus 

 reduciug the supratemporal foramen. This occurs also in Gerrhonotus, 

 Celestus, Xenosaurus^ and Xantusiidie. In Heloderma tlie supratem- 

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

 The remarkable ujjward production of the supratemporal in Chamcc- 

 leon has been mentioned. Here this process takes the place of the 

 parietoquadrate arch. The exoccipitals are produced laterally, each 

 embracing, with the petrosal in front, the small paroccipital. This sus- 

 tains the suiDerior extremity of the quadrate. In the snake-like genera, 

 as Feylinia, Anniella, and the Amphisbienia, this lateral elongation does 

 not exist. The exoccipital is suake-like, and the quadrate is sessile on 

 the side of the skull. The quadrate is generally convex at the upi)er part 

 of its anterior face, and its external anterior border is produced outward 

 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 backward. In the Iguanidte 

 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 Yara- 

 nidaj and Helodermidie, and in Phrynosoma, Uuhlepharisj-and Celestus 

 it is wanting. In Chanueleon, Afmiella, 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 j^lane. In Gecko 

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

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

 in contact in all forms except Chamccleon, toward the middle line. This 

 portion is generally grooved, but in Xenosaurns it is a slender rod. They 

 are received on the basipterygoid processes of the sphenoid, and then 

 diverge and assume a longitudinal position without meeting on the middle 

 line. They are produced in an angle or process toward the posterior 

 extremity of the maxillary bone, from which they are separated by the 

 ectopterygoid. The i)tery golds then join the palatines. In a few genera 

 they bear a few small teeth. The palatines are separate from each other 

 and from the maxillaries, but send a process outward and forward to 

 the latter. They join in front each its corresponding half of the vomer. 

 The internal nares are situated each between the vomer and the maxil- 

 lary, and it notches more or less deeply the palatine, which forms its 

 posterior border. The vomers are separate in all forms excepting 

 Chamccleon, and they have various I'orms. In Geckonid;e and Anolidiie 

 they are flat and fit closely together, and they have the same character 

 iu many Agamida3 and Iguanidte. In a few members of these families 

 [Uromastix and SauromaJm) they are divided by a groove, which 

 becomes a fissure posteriorly, which is the character in most other liz- 

 ards. In the A^aranid;e each vomer is produced posteriorly on each side 

 this fissure to a greater distance than in other forms. The j^lanes of 

 the ijalate differ much iu dillerent families and groups. Thus, the vomer 



