ON THE OCCURRENCE OF PLACBNTATION IN THE SCINCID LIZARD LYGOSOMA ENTRECASTEAUXI. By Launcelot Hakrison, B.A., B.Sc, Challis Professor, and Hazel C. Weekes. (From the Department of Zoology, University of Sydney.) (Plates xlvii-xlix and three Text-figures.) [Read 25th November, 1925.] Contents. i. Introductory, ii. Material and methods, iii. Anatomical relations, iv. The Placentae. V. Comparison with Chalcides. vi. Theoretical considerations, vli. Summary and Conclusions. i. Introductory. During the visit of a party from the University of Sydney to Barrington Tops in January and February of this year (1925) under tlie leadership of the senior author. Dr. I. M. Mackerras, who was examining the reptiles obtained for Haemoprotozoa, discovered that two of the common skinks present, Lygosoma quoyi Dum. et Bibr., and L. entrecasteauxi D. & B., were viviparous, and were carrying advanced young. In view of the possible interest of this discovery, a series of both species was collected. The former of these species has already been recorded as viviparous by Lucas and Frost (1893), but these authors state that the latter species is oviparous in Victoria, laying from three to five eggs in January. This suggests a possible difference in reproductive habit on high and low ground, which, should it be confirmed, offers points of curious interest. The reproductive phenomena of Australian reptiles have attracted small attention from workers in zoology, so that little precise information exists con-cerning oviparity and viviparity amongst the different groups. Lucas and Le Souef (1909) mention that most of the venomous snakes are viviparous, but quote only two lizards as being so, viz., Tiligua nigrolutea and Trachysaurus rugosus, both belonging to the Scincidae. Lucas and Frost (1893) have, how-ever, recorded four other skinks as viviparous. The remaining families of lizards occurring in Australia, viz., Geckonidae, Pygopodidae, Agamidae, and Varanidae are, as far as is at present known, all oviparous. Amongst the skinks, we now know the following species to be viviparous: — TracJiysaurus rugosus Gray Rec. by Haacke (1885) Tiligua scincoides White „ „ do. Tiliqua nigrolutea Gray „ ,, Lucas & Le Souef (1909)
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