CROCODILIANS, LIZARDS, AND SNAKES. 485 



Four families are referable to tlie Dlploglossa, which are defined as 

 follows. The position of the Pygopodidte is somewhat uncertain : 



I. Apex of tongue not retractile. 



Cranial arches present; interclavicle cruciform; orbit bounded by frontal bone; 

 corpus adiijosum projecting freely into body-cavity Zonukid.e 



Cranial arches absent; interclavicle rudimental are wanting; iirefrontal and 

 postfrontal united above orbit; articular, angular, and surangular bones not 

 distinct Pygopodid.k 



II. Apex of tongue retractile. Corpus adiposum entirely adherent. 



Cranial arches present; no inferior frontal arch; interclat^icle cruciform; teeth 

 nleiirodont; osteodermal plates AxGUiD.K 



Cranial arches present; no inferior frontal arch ; interclavicle cruciform ; teeth 

 pleurodont ; no osteodernial plates Xenosaurid.e 



The families of Section I are Old World, the Zonuridae belonging to 

 the Ethiopian zoological realm, and the Pygopodidic to the Australian. 

 The remaining families are Xew World, except that among Auguidie 

 three genera belong to the palaearctic realm. 



ZONUKID.E. 



Cordyloidea Fitzinger, part, Neue Classif. Rept.,'1826, p. 18. 

 Autarckoglossd' Wagler, part, Syst. Amph., 1830, p. 152. 

 Chamwsauri, Ptychopleurl Wiegmann, part, Herp. Mex., 1834, pp. 11, 29. 

 Chalcidiens Dumeril and Bibron, part, Erp. Gen., V, 1839, p. 318. 

 Zonuridw, ChanKvsaurida Gray, part, Cat. Liz., 1845, pp. 4, 45, &1. 

 Zoniiridw Cope, part, Proc. Am. Assoc. Adv. Sci., XIX, 1871, p. 236. 

 ZoH«rWrt' Boulenger, Ann. Mag. Nat. Hist. (5), XIV, 1884, p. 119; Cat. Liz. Brit. 

 Mns., 2d ed., II, 1885, p. 251. 



Tongue short, villose, scarcely protractile, entire or very feebly nicked at the end. 

 Dentition pleurodont; teeth numerous, small, with long cylindrical shafts, hollowed 

 out at the base. Palate toothless. Postorbital and frontosquamosal arches bony; 

 snpratemporal fossa loofed over by dermo-osslfication ; pr;pmaxillary, frontal, and 

 parietal single; nasals distinct; iialatinesand pterygoids widely separated mediallj-, 

 both bordering the infraorbital fossa; head with dermal bony shields. Clavicle 

 slender, not dilated proximally; interclavicle cruciform; sternum without fonta- 

 nelle. No abdominal ribs. Head symmetrically shielded. Eyelids well developed. 

 Scales on the body, if not granular, arranged in transverse series. Osteodermal 

 plates present in one genus, but devoid of distinct tubules. 



Like the preceding, this family has ])oint8 of resemblance with the Iguanida' and 

 with the Anguidie. From the former it is distinguished bj^ the cranial dermal ossi- 

 fications and the cruciform interclavicle," from the latter by the tongue, which, like 

 that of the Iguanida', is not divisible into an anterior and a posterior part, the 

 Cttdodont dentition, and the structure of the bony plates of the body when present. 

 (Boulenger.) 



Six genera are known, inhabiting South and tropical Africa and 

 Madagascar. 



