THE COMPARATIVE OSTEOLOGY OF AUSTRALIAN GECKOS AND ITS BEARING ON THEIR MORPHOLOGICAL STATUS

Abstract

Summary 1. Representatives of 11 genera of geckos occurring on the Australian mainland are studied from alizarin transparencies. 2. Comparisons are made with New Zealand, New Guinea, Solomon Island and Jamaican forms. 3. As far as skull structure is concerned, a neotenic condition appears to be widespread and occurs in many of the genera. 4. Scleral ossicles exhibit much variation not only between genera, but also, in certain cases, between young and old individuals of the same species, and even between right and left eyes of a single individual. 5. Among the Australian genera examined, in no case is there complete continuity in the second branchial arch. In general, hyobranchial structures show considerable similarity at the generic level. 6. The pectoral girdle is fairly distinct from genus to genus, mainly because of the variation in the shape of the interclavicle and in the relationship of sternal ribs to the sternal plate. 7. The typical reptilian phalangeal formula occurs in most cases. The genus Nephrurus, however, is unique in that the phalangeal formula for Nephrurus asper is 2, 3, 4, 4, 3 for the fore limbs and 2, 3, 4, 4, 4 for the hind limbs. In Nephrurus laevis, it is 2, 3, 3, 3, 3 for both fore and hind limbs. 8. It has not been possible to find osteological characters which would support the division of the Geckonidae based on ophthalmological features, or justify the dispersal of the Australian genera in to separate subfamilies, according to the shape of the eye, as suggested by Underwood (1954).