118 Mr. G. A. Boulenger on the 



rated as a suborder, or even as an order, I include among the 

 true lizards, and regard them as a degraded type of the 

 Teiidffi, with which they are to some extent connected by the 

 Chalcides and their allies. The principal characters which 

 have been put forward in favour of their separation are : — 

 (1) absence of interorbital septum ; (2) absence of columella 

 cranii ; (3) very short mandible, causing the quadratum to be 

 nearly horizontal ; (4) division of the occipital condyle; (5) ab- 

 sence of postorbital and fronto-squamosal arches; (6) absence 

 of scales. These characters, which are mostly negative, are 

 not all constant throughout the group, and many will be found, 

 to a greater or less degree, to be characteristic of all strongly 

 degraded, burrowing forms, such as Aniella near the 

 Anguidffi, AneJytrops [Typhline) and Dibamus near the 

 Skinks, &c. The im])ortance of these characters justifies our 

 placing the Amphisba^nas in a separate family ; but, in my 

 opinion, not in a higher group, for the following reasons : — 



1. The absence of interorbital septum also occurs in 

 Ophiognomon among the Teiidse, and there is every grada- 

 tion between the skull of that genus and that of higher 

 members of the same family : besides Aniella and Dibamus^ 

 which belong to totally different families, also possess the 

 same negative character. 



2. The columella disappears gradually witlithe interorbital 

 septum ; it is hardly distinguishable in Ophiognomon and 

 totally absent in Aniella and Dibamus. 



3. The aberrant lower jaw, not in itself a very important 

 character, is not even constant, the genus Blanus differing in 

 that resjDCct as much from the typical AmpJiisbcena as from 

 a typical Lizard. 



4. The division of the occipital condyle, also a character 

 the importance of which ought not to be exaggerated, is not 

 even constant, the Acrodont Amphisbanians forming ex- 

 ceptions. 



5. The absence of postorbital and fronto-squamosal arches, 

 which occurs in the most diverse groups of Lizards, cannot be 

 regarded as more than a family character. 



6. The naked integuments (if we may apply this term to 

 the skin of the Amphisbgenians with its soft scales) are not 

 special to the group, but occur also in Geckos ; and they are 

 so closely approached by those of some Cercosaurine and 

 Chalcidine Teiidas as to render any sharp distinction im- 

 possible. 



On the other hand, characters such as are afforded by the 

 tongue, which in all Amphisbffinians is in every respect 

 similar to that of the Cercosaurine and Chalcidine Teiidiv, 



