Summary1The systematic position of Gekkonidae is considered, and the need for careful assessment of basic criteria such as amphicoely and procoely is stressed.2The procoelous centra ofPhyllurus miliiandSphaerodactylv parkeriare similar to one another and to those of amphicoelous geckos in possessing a continuous notochord, interrupted only at the atlanto‐occipital joint, and the full complement of inter centra, but differing from amphicoelous forms in that they bear a rounded condyle posteriorly.3Tables of vertebral counts made on 151 geckos, representing 20 genera and 31 species are given.4The laterally projecting processes on the atlantal neurapophyses are considered to be serially homologous with the postzygapophyses of following vertebrae; the low processes on the arch pedicels are regarded as parapophyses.5The axial neurapophyses bear parapophyses and reduced prezygapophyses.6Rudimentary ribs may occur on the third cervical vertebra. The ribs of the fourth, fifth and sixth vertebrae usually bear cartilaginous processes inappropriately termed ‘uncinate processes’. The triangular bony process on the proximal portion of the ribs of the seventh vertebra of some genera, also inappropriately termed an ‘uncinate process’, is considered to represent a state transitional between the ribs typical of the cervical and dorsal series. Presence of sacral and caudal ribs is confirmed.7Ribs normally arc attached to the vertebra by means of an articulation between rib head and parapophysis of neural arch, and two ligaments, one above and one below the articulation. Dorsal ligament is considered to be homologous with the tuberculum, and rib head with capitulum.8In most geckos fracture planes occur in all postpygal vertebrae. Geckos with a distinct constriction in the tail at junction of pygal and postpygal series, have fracture planes only in this region;Nephrurus asperhas no fracture planes at all. Last two conditions may be regarded as specialized.9In geckos with a constricted tail, the last pygal neural spine is enlarged, and the two chevrons immediately preceding the first fracture plane are joined together by a bridge of cartilage.10No great morphological change is required for transition from amphicoely to procoely in geckos, and amphicoely is regarded as ancestral to procoely. Procoelous vertebrae ofPhyllurus miliiandSphaerodactylus parkeriare only slightly removed from the amphicoelous condition. There is no evidence of degeneracy in the vertebral column of amphicoelous geckos; living Gekkonidae as a whole are regarded as an ancient lacertilian group.11Procoely is considered to have arisen at least three times in the Gekkonidae– first, in ancestors ofColeonyxand related forms; second, in the series leading toSphaerodactylus; and third in the Australian speciesPhyllurus milii. Probable course of evolution of procoely in geckos is described.12Arguments are presented against placing all procoelous geckos in one subgroup, the Eublepharidae, regardless of affinities with amphicoelous forms. Nevertheless amphicoely, in relation to geckos as a whole, is considered to retain the palaeotelic weight ascribed to it by