Families of existing Lacertilia. 121 



rudimentary have a large interclavicle. To this very im- 

 portant character is added another ; the nasals are united into 

 a single bone, a peculiarity which is found elsewhere only in 

 the VaranidiB among recent lizards. A single genus, Uro- 

 ^jlates^ from Madagascar, is known. 



After the Uroplatida? I have placed the Pygopodidce 

 (=Pygopid8e + AprasiadtB + Lialisidge of Gray), which family 

 is now based on new characters. They were formerly arranged 

 with or near the " Sciucoids," a view which cannot be main- 

 tained, since that group was an assemblage of forms having 

 totally diiferent affinities, and " Scincoids " will now be found 

 scattered through the following families : — Anguidee {Anguisj 

 Dijiloglossus, &c.), Aniellidge, Teiidaj {Gymnoplithalmus^ &c.), 

 Scincida3, Anelytropidaj, and Dibamidee. The skull of the 

 Pygopodida3 in its simplicity of structure approaches that of 

 the Geckos, and the parietal bones remain distinct in all the 

 genera except Lialis ; the bones of the lower jaw are still 

 more reduced in number, the angular, supra-angular, and arti- 

 cular having coalesced, a character by which they approach 

 the snakes. The affinities of this little group are very obscure, 

 and a complete investigation of their anatomy is highly 

 desirable. 



The two closely allied families Agamidce and Iguanidce 

 remain as before. 



The Xenosaivridce must be regarded as intermediate between 

 the Iguanidte, with which Peters was inclined to associate 

 them, and the Anguidffi, near which they are placed by Cope. 

 The Zonuridoi correspond only in name with the Zonu- 

 rida3 of Gray and most other authors. The members of 

 Gray's Zonuridaj will be found in the following families : — 

 Anguidai {GerrhonotuSy FseudojJus, &c,), Lacertidai [Tachy- 

 dromus), Gerrhosaurida3. They have, like the Anguidai, a 

 villose tongue, though not retractile at the end, a slender 

 chavicle, and in some the body even presents bony plates, 

 which arc destitute of symmetrical canals. As here under- 

 stood, the Zonurida3 comprise the genera Zonurus, Flaty- 

 saurus, and Cliavicesaura. 



The Anguidce correspond to Cope's Anguidas and Gerrho- 

 notidte, the diiferential characters of which latter group seem 

 to me insufficient for family separation. As Cope has shown, 

 this group is perfectly natural, though containing " Chalci- 

 doid" and " IScincoid " forms, and an excellent illustration 

 of how misleading it is to trust only to external characters. 

 The " Scincoid " forms correspond to Bocourt's Diplo- 

 glossidce. 



The family Aniellidce was also established by Cope. I 

 would regard it as a degraded form of the Anguidse. 



