The lizard genus Aprasia

The genus Ophioseps cannot be maintained ; its past recognition was due to errors of identification and observation.Aprasia is the most completely adapted of the Pygopodidae for fossorial life, the family exhibiting a continuous series in degeneration of limbs and girdles, with the development of a serpentiform habitus and cranial modifications for burrowing.There are three species with a combined range from Victoria to the Monte Bello Islands but which occur together in only a restricted area near Albany.Two of the species show a considerable range of variation in the numbers of presacral vertebrae and scales.This variation appears to be correlated with differing summer temperatures.Since the characters are meristic and such characters have been shown, in other cold-blooded animals, to be directly affected by the temperature prevailing during embryological development, it is suggested that the variation may prove to be thermoplastic.The other taxonomically useful, but non-meristic, characters show no significant variation in different climatic regions.The temperature correlated clines are discontinuous geographically, permitting recognition of two new subspecies.Two small limbless lizards were collected on Hermite Island, one of the Monte Bello group, in 1952.They differ from any of the known species of the genus Aprasia but most nearly resemble Aprasia repens Fry.Since the Monte Bello Islands are geographically far removed from the recorded range of any species of Aprasia a re-survey of the known species of the genus, and its alleged ally Ophioseps, was necessary to ascertain the probable significance of the differences.More than 120 specimens were assembled for comparison, and this series covered not only the whole of the previously known geographical range, but included recently captured specimens from regions where none of these lizards had previously been reported. MORPHOLOGY AND COMPOSITION OF THE GENUSAs will be demonstrated presently the series is subdivisible into five groups with morphological differences, but all the specimens share the following characters :Scales smooth, subequal dorsally and ventrally except on the throat and pectoral region, where they are slightly smaller than on the belly ; 12 or 14 longitudinal rows of scales at mid-body.General habitus worm-like, the head and tail not being wider or narrower than the body, which is very elongate and cylindrical.The snout projects in front of the labial margin and the large rostral shield is visible ZOOL.3, 9. 24