2 LACEETILIA. 



Fam. 5. Agamidse. Postorbital and postfronto-squamosal arches 

 — present ; supratemporal fossa not roofed over by bone ; 



tongue thick ; aorodont. 



Fam. 6. Iguanidae. Postorbital and postfronto-squamosal arches 

 present ; supratemporal fossa not roofed over by bone ; 

 tongue thick ; pleurodont. 



Fam. 7. XenosauridEe. Postorbital and postfronto-squamosal arches 

 present ; supratemporal fossa not roofed over ; anterior por- 

 tion of tongue retractile, j i 



Fam. 8. ZoniLrida8. Postorbital and postfronto-squamosal arches 

 complete ; supratemporal fossa roofed over ; tongue simple. 



Fam. 9. Anguidse. Postorbital and postfronto-squamosal arches 

 present ; supratemporal fossa roofed over ; body with osteo- 

 dermal plates, each provided with a system of irregularly 

 arranged arborescent or radiating tubules ; anterior portion 

 of tongue retractile. 



Fam. 10. Auiellidae. No interorbital septum, no columella cranii, 

 no arches. 



Fam. 11. Helodermatidse. Postorbital arch present, postfronto- 

 squamosal arch absent ; pre- and postfrontals in contact, 

 separating the frontal from the orbit. 



|-KFam. 12. Varanidae. Postorbital arch incomplete ; postfronto- 

 squamosal arch present; supratemporal fossa not roofed 

 over ; nasal bone single ; tongue deeply bifid, sheathed 

 posteriorly. 



C. Tongue covered with imbricate scale-like papillae or with 

 oblique plicae ; clavicle dilated proximally, frequently loop- 

 shaped. 



Fam. 13. XantusiidaB. Parietals distinct ; postorbital and post- 

 fronto-squamosal arches present ; supratemporal fossa roofed 

 over. ' !-^ 



Fam. 14. Teiidae. Postorbital and postfronto-squamosal arches 

 present ; supratemporal fossa not roofed over ; no osteo- 

 dermal plates. 



Fam. 15. AmpMsbsenidsB. No interorbital septum; no columella 

 cranii ; no arches ; premaxillary single. 



Fam. 16. Lacertidffi. Arches present ; supratemporal fossa roofed 

 over; premaxillary single; no osteodermal plates on the 

 body. 



Fam. 17. Gerrhosauridae. Arches present; supratemporal fossa 

 roofed over; premaxillary single; body with osteodermal 

 plates, each provided with a regular system of tubules (a 

 transverse one anastomosing with longitudinal ones). 



