21/6/38 Notes on First Reconnaissance Flight. Xeric brushes of limestone hills along coast are restricted to the coastal slopes. Rain-forest, rather pale in cutover, succeeds them immediately inland. North shores of Lake Sentani largely low, swampy and carrying sago. South shores generally ridgy. Large areas of ridges round the lake are devoid of trees and covered with grass. These grass- lands a secondary condition following disturbance by native cultiva- tion, and are maintained by fire. On outward journey population was seen to extend into the hill country 6 minutes. On return the first houses were seen 17 minutes out from W. end of lake. Between Lake Sentani and the Idenburg all rain-forests, elevated to ± 1000 m.: rock probably limestone. Idenburg a big winding muddy river: banks partly forest and part- ly grass (care and reeds?). No population seen on river: but most of the country from Sentani to the mountains hidden under a cloud field. Upper surface clouds over Idenburg 700 m. at 9:20 A.M. First line of mountains rises very steeply from the Idenburg: but spurs well defined. North side of the Angimoek wooded almost to summit: on south side a brown grassy plateau perhaps 200 acres in area: 2 small ponds on this plateau. Practically every valley on our course between Doorman Top and Lake Habbema carried some population. Very little closed forest, and that only in sheltered places, seen on high plateau about Lake Habbema. The ridges carry shrubberies in which grow numerous slender trees. The hollows grassy, full of ponds, marshy, and drained by winding streams. Ponds also plentiful