A pectoral girdle and sternum may be present, or may be completely absent as in snakes. Except in snakes there are generally four pentedactylate limbs which may either form paddles or be adapted for walking. _Suborder (1)._ LACERTILIA[77]. The body is elongated, and as a rule four short pentedactylate limbs are present, but sometimes limbs are vestigial or absent. The exoskeleton generally has the form of horny plates, spines, or scales; while sometimes as in the Chamaeleons and Amphisbaenians it is absent. In other forms such as _Tiliqua_ and _Scincus_, the body has a complete armour of bony scutes, whose shape corresponds with that of the overlying horny scales. The vertebrae are procoelous, rarely as in the Geckos amphicoelous; they are usually without zygosphenes and zygantra, but these structures occur in the Iguanidae. The sacral vertebrae of living forms are not ankylosed together, and the caudal vertebrae usually have well-developed chevron bones. In the skull[78] the orbits are separated from one another, only by an imperfectly developed interorbital septum, the cranial cavity not extending forwards between them, while the alisphenoidal region is unossified. The premaxillae may be paired or united (Amphisbaenidae), and there is usually an interparietal foramen. There may be a complete supratemporal[79] arcade bounding the lower margin of the supratemporal fossa, or the supratemporal fossa may be open below. The quadratojugal is not ossified, and the quadrate articulates with the exoccipital. There is no infratemporal arcade. There is commonly a rod-like epipterygoid[80] (fig. 33, 14) connecting the pterygoid and parietal. Teeth are always present, and may be confined to the jaws or may be developed also on the pterygoids and rarely on the palatines; they are either acrodont or pleurodont. The rami of the mandible are suturally united. A pectoral girdle is always present, and generally also a sternum. Clavicles and a T-shaped interclavicle are commonly present, but are absent in the Chamaeleons. [Illustration FIG. 33. A, LATERAL VIEW, AND B, LONGITUDINAL SECTION OF THE SKULL OF A LIZARD (_Varanus varius_). × 3/5. (Brit. Mus.) 1. premaxillae. 2. maxillae. 3. nasal. 4. lateral ethmoid. 5. supra-orbital. 6. lachrymal. 7. frontal. 8. postfrontal. 9. prefrontal. 10. basisphenoid. 11. pro-otic. 12. epi-otic. 13. pterygoid. 14. epipterygoid (columella cranii). 15. jugal. 16. transpalatine. 17. parasphenoid. 18. quadrate. 19. parietal. 20. squamosal. 21. supratemporal. 22. exoccipital. 23. dentary. 24. splenial. 25. supra-angular. 26. angular. 27. coronoid. 28. articular. 29. vomer. 30. basi-occipital. 31. orbitosphenoid.] There is no separate precoracoid but a precoracoidal process (fig. 34, 7) of the coracoid is generally prominent.