36 RUDOLF SÖDERBERG, STUDIES OF THE BIRDS IN NORTH WEST AUSTRALIA. 
Ralliformes. 
Fam. Rallide. 
Microtribonyx ventralis GouLpD. 
Math. handl. n:r 59. 4 SSI ad. Nooncanbah ?/12, ?"/12 1910; 8/1, ?6/1 1911; 1 8 ad. ?7/12 1910, moult. 
Moulting. — Two specimens of ””/h2, ”h are partly moulting on neck and 
back. No wing- or tail-feathers have yet been dropped. The other specimens have 
somewhat worn but clean and full-coloured plumages. 
Ecological. — Among the birds which came to Mowla Downs at the same 
time as the rain was Microtribonyx ventralis. The 25th of Nov. I observed it for 
the first time, in a pool of water edged with low bushes near our camp. From that 
time it began to be rather common, and I saw it in ägt places in the bush. 
Up at the river it was common too. 
Lariformes. 
Fam. Laridae. 
Hydrochelidon hybrida Par. 
Math. handl. n:r 119. J juv., 2 juv., Soil Creek, Meda, Derby ?4/5 1911, change of plumage. 
These. two juvenal-birds were shot a little inland at Meda. Adults were also 
seen fishing in and plunging into the fresh-water pools and creeks there. 
Gelochelidon anglica MONT. 
Math. handl. n:r 120. SJ ad. Derby, Kimberley ?/e 1911; 3 229 ad. Beagle bay, Dampier land ?!/; 1911. 
All the specimens were adults and have winterplumages. Common at the 
coast in wintertime. 
Hydroprogne caspia MOoNnr. 
Math. handl. n:r 121. 2 SS ad., 2 29 ad. Broome, Dampier land 9/6, ?!/6 1911. Moult. in wing. 
Plumage. — All the birds were adults and in winterplumage. The white patch 
of the forehead is not developed in one spec. but appears only as spots in the edges 
of the black feathers. In other birds the winter-colour of the head appears in pins 
which are black, also with white in the margin. Hence the birds get white fore 
heads with black middle parts of the feathers. 
