GERRHOSAURIDA, 119 
Fam. 17. GERRHOSAURID. 
Scincide, part., Anguide, part., Gray, Ann. Phil. (2) x. 1825. 
Ophisauroidea, part., Fitzinger, Neue Classif. Rept. 1826. 
Autarchoglosse, part., Wagler, Syst. Amph. 1880. 
Ptychopleuri, part., Wegmann, Herp. Mex. 1834. 
ee Ptychopleures, part., Duméril § Bibron, Erp. Gén. v. 
839. 
Zonuride, part., Gray, Cat. Liz. 1845. 
Zonuride, part., Cope, Proc. Am. Assoc. Adv. Sc. xix. 1871. 
Gerrhosauride, Boulenger, Ann. & Mag. N. H. (5) xiv. 1884. 
Tongue’ moderately elongate, bifid posteriorly, free and very 
feebly nicked anteriorly, covered with imbricate scale-like papille 
or oblique plicee converging anteriorly towards the median line. 
Dentition pleurodont ; teeth closely set, with long cylindrical 
shafts, hollow at the base, with conical or bicuspid ciowns. Ptery- 
goid teeth often present. 
Skull in every respect similar to that of the Lacertide, with 
dermal ossification roofing over the supratemporal fosse. Limbs 
well developed or rudimentary. Clavicle dilated and loop-shaped 
proximally ; interclavicle.cruciform. Tail long and fragile. 
Head with symmetrical shields. Body with squarish or rhom- 
boidal imbricate scales, which often form regular longitudinal and 
transverse series; it is besides protected by osteodermal plates, un- 
derlying the scales, which show a system of longitudinal tubules 
intersecting a transverse one, as in the Scincide; this structure 
usually more distinct on the ventral plates than on the thicker and 
rougher dorsal ones. A lateral fold, with granular scales, similar 
to that of Gerrhonotus, is present in all genera except Trache- 
loptychus, which in its scaling more resembles the Scincs. 
Femoral pores constantly present. Lyelids well developed. Tym- 
panum distinct. 
This family is exactly intermediate between the Lacertide (single 
premaxillary, femoral pores) and the Scincide (presence and struc- 
ture of the dermal bony plates). It is strictly African, its head- 
quarters being South Africa and Madagascar, and extending north- 
wards to the southern limit of the Sahara. 
Synopsis of the Genera. 
I. Nostril pierced between two nasals and the first labial; ventral 
plates forming straight transverse series. 
Tongue nearly entirely covered with imbricate scale-like papille ; 
prefrontals and frontoparietals present ; lower eyelid scaly. 
1. Gerrhosaurus, p. 120. 
Tongue nearly entirely covered with oblique plice ; no prefrontals ; 
frontoparietals present; lower eyelid scaly; limbs short or 
rudimentary ........e0.. ee ee 2. Tetradactylus, p. 124. 
