L. 25, P. 3 breeding condition was one ringens which had three embryos. A number of ringens females were not quite fully grown, the same being the case with R. brachyrhinus and M. muscalis. One brachyrhinus juvenile. Went this morning to look at the limestone exposure. Started at the waterholes and worked down the bed of the stream. Came on first exposures a few hundred yards down. One place with a five-foot waterfall (when there is any water to run). The waterhole stream is only a tributary of the main one up which Rand and I went at high tide in the dinghy. The main channel bends away to WNW. Got some strikes and dip angles approximately. But limestone badly mashed up and quite a bit folded. One good syncline exposed. Strikes all approximately NNW; dips varying from nil to as steep as 35 degrees. None of this appears on the savannas, so it seems likely that the region must be classed as a peneplain, the clayey surface soil being being residue of limestone and possibly of any beds that may once have overlaid it. The time to see structure here is at low tide. I can account for the tidal or estuarine nature of this region only by supposing it drowned land. Wonder whether the peculiar form of Strachan Island with its surrounding tidal waters may not be due to its once having served as the mouth of the Fly R. The point of turn-off would be somewhere above the Fairfax islands, and the latter could be brought about through pirate drainage and slight warping of the general earth level. The limestone has no obvious fossils in it, but may contain micro- fossils. The bed of the stream contains a fair number of potholes. The limestone where not water worn appears greatly cracked and jointed. In the afternoon Rand and I went by dinghy for about four miles up the SW branch. The river goes south; west; south; west; S and on around to ESE; then back to a long WSW stretch; an S-loopto the right and again WSW. On the next corner a fair sized creek enters on the river's right bank, the main stream turning NW. We entered the creek and landed on its east shore a few hundred yards up. Behind a fringe of trees a few yards wide we found the usual level, burnt-over tree savanna. Rand shot a Pipistrellus which was flying above the creek. The river thus takes in the main a series of right-angle turns, probably conforming in part with the geological structure of the underlying limestone The high places naturally occur at the bends, turning the stream into each new course; but those high places mark little more than where the peneplane, or perhaps a slight anticlinal fold is butted against by the river. The intervening points have high land behind them too a score or so of yards behind the water-loving Nipa palms which give those parts of the river its characteristic swampy appearance. Mangroves appear mixed with or in stands replacing the Nipa. Mon. Dec. 7. Two boys out with colds and fever yesterday, but the other two (Gororo and Taikudo) have been pinch-hitting for them and brought in 7 and 8 specimens respectively. 4 ringens, 6 brachyrhinus, 3 muscalis, and (what I'm very pleased to see) 2 specimens of the Phasogale of the Daviumbo camp. Both (males) were trapped in long-grass savanna. The brachyrhinus comprise one large female with three embryos, 1 y. ad. f., the rest being juvenals of the past breeding season. Went down the waterhole stream but found nothing in particular. In p.m. burned sulzhr in a couple of hollow trees but nathing in them. Went jacking in evening. Shot only two night hawks and a kingfisher which is the second specimen of a new species according to Rand. Swarms of winged termites buzzing around my light. Tues. Dec. 8. 14 specimens in traps: 4 brachyrhinus, 9 ringens and another Phasogale. The last without any young in pouch. Heavy rains during night. The local policeman (one who came from Daru