lACERTILIA. 53 



osteodermal plates, each provided with a sys- 

 tem of irregularly arranged arborescent or radi- 

 ating tubules ; anterior portion of tongue 



retractile ; pleurodont , Fam. 4. Anguidae. 



Postorbital arch incomplete ; postfrouto-squamosal 

 arch present ; supratemporal fossa not roofed 

 over ; nasal bone single ; tongue deeply bifid, 

 sheathed posteriorly .Fam. o. Varanidae. 



C. Tongue covered with imbricate scale-like papillte or with obhque 

 plicjB ; clavicle dilated proximally, frequently loop-shaped. 



Postorbital and postfrouto-squamosal arches present ; 

 supratemporal fossa roofed over ; praemaxillary 

 single; no osteodermal plates on the body. Fam. 6. Lacertidaa. 



Postorbital and postfrouto-squamosal arches present ; 

 praemaxillary double ; body with o.steodermal 

 plates, each provided with a regular system ot 

 tubules (a transverse une anastomosing with 

 longitudinal ones) Fam. 7. Scincidae. 



No interorbital septum : no columella cranii ; no 

 arches; pnemaxillary double; no osteodermal 

 plates Fam. 8. Dibamidae, 



The following is an artificial key, based upon characters which 

 are readily observable \Aithout any kno\^ledge of the internal 

 structure of tlie animals, and by which any Lizard occurring within 

 the area ascribed to this fauna may be referred to the family to 

 which it belongs : — 



A. Tongue smooth or with villose papilhe, 



short or moderate, not sheathed at the 

 base (see fig. 20, p. 5')). 



a. Head covered with granules or small 



scales ; body without bony armour. 



No movable eyelids ' 1. Geckonidae, p. 54. 



Movable, connivent eyelids ; dorsal scales 

 granular and tubercular, round, jux- 

 taposed ; pui)il vortical 2. Eublepharidae, p. 107. 



Movable, connivent eyelids ; dorsal .scales 



mo.stly imbricate ; pupil round .... '•*>. Agamidae, p. 109. 



b. Head with symmetrical shields above; 



body rigid, with bony plates under- 

 lying the scales \ 4. Anguidae, p. lo8. 



B. Tongue much elongate, sheathed at the 



base, similar to that of Snakes ; head 



covered whh small scales 5. Varanidae, p. ICO. 



C. Tongue covered with imbricate scale- 

 like papilla3 (see fig. 51, p. 167) or oblique 

 plicae ; head with symmetrical shields. 



a. Eyes exposed. 



Ventral scales much difterentiated from 



the dorsals ; femoral or prteanal 



pores 6. Lacertidae, p. 1G7. 



Body covered with cycloid imbricate 



scales ; no femoral or prgeaual pores 7. Scincidae, p. 180. 

 Eyes hidden under the shields 8. Dibamidae, p. 229, 



