122 On the Families of existing Lacertilia. 



The Helodermatidce, as already shown bj Cope, have tlie 

 greatest affinity to tlie AnguidaB, from which they are, how- 

 ever, well distinguished by the structure of the skull. The 

 grooved teeth might be given provisionally as another family 

 character. It would be highly irajjortant to have some infor- 

 mation on the osteological characters of Steindachner's Lan- 

 thanotidte, as tliere is reason to suspect they will enter this 

 family. 



The Varanidce, which come last in the series of alepidote- 

 tongued lizards, remain characterized aa before, and form a 

 perfectly isolated group. 



We have next a series of families characterized by the 

 peculiar scale-like lingual papillas and the proximally dilated 

 clavicle. 



The XantusiidcB are closely allied to the Teiid^, but 

 distinguished by the different skull and scarcely incised tongue. 



The Teiida form a very natural group, comprising the 

 Cercosauridai, Chalcididaj, Chirocolida;, Anadiadaj, and part 

 of the Gymnophthalmida3 of Gray and the Tretioscincidas of 

 Bocourt. It thus contains " Lacertoid," " Chalcidoid," and 

 *' Scincoid "" forms of the Dumerilian system, all passing into 

 one another by insensible gradations and all agreeing in the 

 structure of the skull, tongue, and pectoral arch. All are 

 confined to the New World, whereas the analogous family 

 Lacertid(B is restricted to the Old World. As mentioned 

 above, I regard the Amphisb^nidee as strongly degraded 

 forms of the Teiidfe. 



I establish a family Gerrhosaurida> for GerrliosaicruSy 

 which was formerly associated with the Zonuridaj, but which 

 agrees closely with the Scincidas, from which it is to be dis- 

 tinguished by the coalesced premaxillaries. Although the 

 arrangement of the scales of the body is different from what 

 we see in the latter family, the underlying dermal bony plates 

 are precisely similar in their symmetrical canals. 



The Scincidce correspond to Cope's Scincid^, Sepida?, and 

 Acontiida3, and to Bocourt's group Aspidoscinciens, less the 

 Diploglossidaj. 



The Aneli/tropidce, a small family so named by Cope and 

 synonymous with the Typhlinidas of other authors, are a 

 degraded type of the Scincida?, having completely lost the 

 cranial arches — which, in some forms of the latter group, 

 show a tendency to disappear — and also the osteodermal plates. 



The Dibamidce, characterized for the first time, and com- 

 prising only the genus Dibamus, go still further in the direc- 

 tion of degradation, and are exactly analogous in this series 

 to the Aniellida^ in the other series. 



