LA.CERTILIA. 53 



osteodermal plates, each provided with a sys- 

 tem of irregularly arranged arborescent or radi- 

 ating tuhules; anterior portion of tongue 



retractile ; pleurodont Fam. 4. Anguidse. 



Postorbital arch incomplete ; postfronto-squamosal 

 arch present ; supratemporal fossa not roofed 

 over ; nasal bone single ; tongue deeply bifid, 

 sheathed posteriorly Fam. 5. Varanidae. 



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

 plicae ; clavicle dilated proximally, frequently loop-shaped. 



Postorbital and postfronto-squamosal arches present; 

 supratemporal fossa roofed over ; praemaxillary 

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



Postorbital and postfronto-squamosal arches present ; 

 praemaxillary double ; body with osteodermal 

 plates, each provided with a regular system of 

 tubules (a transverse one anastomosing with 

 longitudinal ones) Fam. 7. Scincidae. 



No interorbital septum; no columella cranii; no 

 arches ; praemaxillary double ; no osteodermal 

 plates Fam. 8. Dibamidae. 



The following is an artificial key, based upon characters which 

 are readily observable without any knowledge of the internal 

 structure of the 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 papillae, 

 short or moderate, not sheathed at the 

 base (see fig. 20, p. 55). 



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 ; pupil vertical 2. Enblepharidae, p. 107. 



Movable, connivent eyelids ; dorsal scales 



mostly imbricate ; pupil round 3. Agamidae, p. 109. 



b. Head with symmetrical shields above ; 



body rigid, with bony plates under- 

 lying the scales 4. Anguidae, p. 158. 



- B. Tongue much elongate, sheathed at the 

 jf base, similar to that of Snakes ; head 



covered with small scales 5. Varanidae, p. 1GO. 



/C. Tongue covered with imbricate scale- 

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

 plicae ; head with symmetrical shields. 

 a. Eyes exposed. 



Ventral scales much differentiated from 



the dorsals; femoral or praeanal 



pores 6. Lacertidae, p. 167. 



Body covered with cycloid imbricate 



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

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



