Sub-Fam. 3. Uroplatinae, composed of a few species of the genus Uroplates in Madagascar. The distinctive characters of these otherwise typical Geckos are the fusion of the nasal bones into one, the small size of the interclavicle, and the non-dilated shape of the clavicles.
Neither the Eublepharinae nor the Uroplatinae are more nearly related to other Autosauri than are the other Geckos. They are modifications within the sub-order of the Geckones.
Sub-Order 2. Lacertae.–Autosauri with procoelous, solid vertebrae, and with the ventral portions of the clavicles not dilated.
Cope,[[153]] discarding outer appearances as deceptive in the classification of the Lacertae, laid stress upon internal characters, notably the presence or absence of osteoderms, the formation of the skull, and the structure of the tongue. Boulenger[[154]] has followed and improved upon Cope's arrangement, and has elaborated the classification, which, being used by himself in the three volumes of the Catalogue of Lizards in the British Museum, has also been followed in the present work, with slight alterations in the order of treatment of the families. For our present purpose we diagnose the families as follows, giving preference to such characters as are most easily ascertained:–
Synopsis of the Families of Lacertae.
| Fam. 1. Agamidae. | Acrodont. Tongue broad and thick. No osteoderms. Old World, p. [515]. |
| Fam. 2. Iguanidae. | Pleurodont. Tongue short and thick. No osteoderms. America, Madagascar, Fiji Islands, p. [528]. |
| Fam. 3. Xenosauridae. | Pleurodont, solid teeth. Anterior part of tongue retractile. No osteoderms on the body. Mexico, p. [536]. |
| Fam. 4. Zonuridae. | Pleurodont. Tongue short, not retractile. With osteoderms at least upon the skull, where they roof in the supratemporal fossae. African sub-region, p. [536]. |
| Fam. 5. Anguidae. | Pleurodont, solid teeth. Anterior part of tongue emarginate, retractile into the posterior portion. Osteoderms on body and head, roofing over the supratemporal fossae. Limbs mostly reduced. America, Europe, India, p. [537]. |
| Fam. 6. Helodermatidae. | Pleurodont, lower teeth grooved, with poison-glands. Tongue bifid. Osteoderms tiny. Postfronto-squamosal arch absent, p. [540]. |
| Fam. 7. Lanthanotidae. | Pleurodont. Tongue short and bifid. Postfronto-squamosal arch absent. No osteoderms. Borneo, p. [541]. |
| Fam. 8. Varanidae. | Pleurodont. Tongue very long, bifid, smooth, very protractile. No osteoderms. Postorbital and temporal arches incomplete. Old World, p. [542]. |
| Fam. 9. Xantusiidae. | Pleurodont. Tongue very short and scaly. No osteoderms. Supratemporal fossa roofed over by the cranial bones. No movable eyelids. Central America and Cuba, p. [547]. |
| Fam. 10. Tejidae. | Teeth solid, almost acrodont. Tongue long, deeply bifid, with papillae. No osteoderms. Limbs sometimes reduced. America, p. [547]. |
| Fam. 11. Lacertidae. | Pleurodont. Tongue long, bifid, with papillae or folds. With osteoderms on the head. Supratemporal fossae roofed over by the cranial bones. Old World, p. [549]. |
| Fam. 12. Gerrhosauridae. | Pleurodont. Tongue long, with papillae, but feebly nicked. With osteoderms on the head and body, roofing over the supratemporal fossae. African sub-region, p. [559]. |
| Fam. 13. Scincidae. | Pleurodont. Tongue scaly, feebly nicked. Osteoderms on the head and body. Limbs often reduced. Cosmopolitan, p. [559]. |
The following five "families" are much degraded in conformity with their usually subterranean life, see p. [496]:–
| Fam. 14. Anelytropidae. | Without limbs. Body covered with scales. Mexico and Africa, p. [564]. |
| Fam. 15. Dibamidae. | Vermiform, limbless body covered with scales, without osteoderms. Australasia and Nicobar Islands, p. [564]. |
| Fam. 16. Aniellidae. | Without limbs; body covered with scales, without osteoderms. California, p. [564]. |
| Fam. 17. Amphisbaenidae. | The body is covered with soft skin, forming numerous rings with mere vestiges of scales. Without limbs, except Chirotes with four-clawed fore-limbs, p. [565]. |
| Fam. 18. Pygopodidae. | Snake-shaped, with scales. Fore-limbs absent, hind-limbs appearing as a pair of scaly flaps. Australia, p. [567]. |
These eighteen "families" of the Lacertae fall into four main groups. We naturally assume that the presence of osteoderms and of complete cranial arches indicate more archaic conditions than their absence, just as we conclude that limbless forms have been evolved from creatures with fully developed limbs. We arrange the four groups with their families as follows:–
| Group I. | Zonuridae and Anguidae assume a central position, with Iguanidae and Agamidae as two parallel families of highest development. Aniellidae as the most degraded forms. Helodermatidae and Lanthanotidae as rather primitive and solitary survivals. |
| Group II. | Xantusiidae–Tejidae–Amphisbaenidae. |
| Group III. | Scincidae–Gerrhosauridae–Lacertidae.–Here also Anelytropidae and perhaps also Dibamidae as degraded Scincoids. |
| Group IV. | Varanidae, which are in many respects the most highly developed of all. |
| Pygopodidae are of obscure relationship. |