Is LACEKTILIA. 



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

 present ; supratemporal fossa not roofed over by bone ; 

 tongue thick ; acrodont. 



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

 present : supratemporal fossa not roofed over by bone ; 

 tongue thick ; pleurodont. 



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

 present ; supratemporal fossa not roofed over ; anterior por- 

 tion of tongue retractile. 



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

 complete ; supratemporal fossa roofed over : tongue simple. 



Fam. 9. AnguidaB. 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. Aniellidae. No interorbital septum, no columella cranii, 

 no arches. 



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

 squamosal arch absent ; pre- and postf rentals in contact, 

 separating the frontal from the orbit. 



Fam. 12. VaranidsB. 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. XantnsiidaB. Parietals distinct; postorbital and post- 

 fronto-squamosal arches present ; supratemporal fossa roofed 

 over. 



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

 present ; supratemporal fossa not roofed over ; no osteo- 

 dermal plates. 



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

 cranii ; no arches ; premaxillary single. 



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

 over; premaxillary single; no osteodermal plates on the 

 body. 



Fam. 17. GerrhosanridaB. 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). 



