The many specimens of this species taken indicate the effectiveness of mist nets in collecting birds in tropical forest. Although Smythies (1960:398) considered this bird to be rare in Borneo, I think that it is merely shy and retiring. We never saw the species in the field and the specimens were all netted. The habitat was in primary forest, except for that of MCT 3300, which was taken in dense secondary forest. The two birds from 12 miles north of Kalabakan were taken in a net stretched across a surveyor's transect. The net was set on a hilltop and the birds hit it approximately three feet above the ground. Two of the specimens from the Cocoa Research Station are in juvenal plumage, indicating that this species probably breeds in the area. _=Cettia whiteheadi=_ (Sharpe): Short-tailed Bush Warbler.--_Specimen_, 1: 5.5 mi. SW Tenom: [Male] testis 3 x 2 mm., December 21, 1962, MCT 3488. The specimen was netted in the moss forest, in fairly heavy secondary undergrowth. _=Prinia flaviventris=_ (Delessert): Yellow-bellied Wren-Warbler.--On September 2, 1962, I saw several of these wren-warblers in a grassy area near the golf course at Tawau. _=Acrocephalus arundinaceus orientalis=_ (Temminck and Schlegel): Great Reed Warbler.--_Specimens_, 6: Tenom: [Female], December 31, 1962, MCT 3546; [Male], January 1, 1963, MCT 3555; [Male], January 2, 1963, MCT 3565; [Female], January 4, 1963, MCT 3575; [Female], January 3, 1963, MCT 3574; [Male], January 4, 1963, MCT 3579. This species was common in the old paddy near Tenom, which has now grown up to grass and shrubs. I saw one individual also in shrubbery in Jesselton. _=Phylloscopus borealis=_ (Blasius): Arctic Leaf Warbler.--I saw this leaf warbler once in dense scrub in the moss forest near Tenom. _=Seicercus superciliaris schwaneri=_ (Blyth): White-throated Flycatcher Warbler.--_Specimens_, 2: 5.5 mi. SW Tenom: [Male] testis 4 x 2 mm., December 23, 1962, MCT 3510; [Female], December 23, 1962, MCT 3511. In the moss forest this was a common bird that hopped about in the climbing bamboo and scrub. _=Orthotomus atrogularis humphreysi=_ Chasen and Kloss: Black-necked Tailorbird.--_Specimens_, 5: Cocoa Research Station: [Male] testis 4 x 2 mm., 6.5 gm., August 28, 1962, MCT 2827; [Female] oviduct enlarged, brood patch, 5.5 gm., August 28, 1962, MCT 2828; [Male] testis 4 x 2 mm., September 26, 1962, MCT 2967; [Female], November 27, 1962, MCT 3336; [Female], November 28, 1962, MCT 3375. These birds lived in the secondary forest-edge in dense shrubbery. They were breeding at a time when most other birds seemed to have completed breeding activities; most had begun the post-breeding (prealternate) molt. On October 3, 1962, I saw two adults with two young in nondescript juvenal plumage with virtually no markings and a pale yellow color, unlike that of the adults.