banks of the Darling.  In the interval they were seen in flocks of from thirty to forty, either soaring in the air or congregated together in trees.  They were never seen to stoop at any thing, nor could we detect on what they fed, but I am led to believe that it was mice.  They are fond of hovering in the air, and in such a position look beautiful, the black bar across the wing underneath them appearing like a W, and contrasting strongly with the otherwise delicate plumage of the bird.  They left us for a time whilst we remained at the Depot, and the first that were afterwards seen by us were on the return of Mr. Browne and myself from our first northern journey.

These birds are widely distributed over that part of the interior traversed by the Expedition.  Like Elanus notatus, it has a bright full eye, the iris inclined to a light pink.  Its shoulders are black, and its back like a sea-gull, slate-coloured.

11.  Circus JARDINII, Gould.—­Jardine’s Harrier.

This bird, with its spotted plumage, was not common.  A specimen was shot on the banks of the Darling, between Williorara and the junction with the Murray.  None of the same bird were seen in the N.W. interior, or to the westward of the Barrier Range.

12.  Strix PERSONATA, Vig.—­Masked Barn Owl.

This fine night bird was very rare in the interior, and only one specimen was procured.  Its plumage is characterised by that softness so peculiar to the genus to which it belongs, and in consequence of which its flight is so silent and stealthy that, like the foot-fall of the cat, it is unheard.

This owl was shot on the Darling, after having been startled out of a tree.

13.  Strix DELICATULUS, Gould.—­Delicate Owl.

Nearly allied to the Strix flammea, or Barn Owl of England.  This bird, widely spread over the continent of Australia, inhabits the interior in great numbers, wherever there are trees large enough for it to build in.  Their young were just fledged when the Expedition descended into the western interior, and at sunset came out on the branches of the gum-trees, where they sat for several hours to be fed, making a most discordant noise every time the old birds came with a fresh supply of food, which was about every quarter of an hour.  It was frequently impossible to sleep from the constant screeching of the young owls.  Their food is principally mice, bats, and large moths.

14.  ATHENE boobook.—­Boobook Owl.

So called from its whoop resembling that sound.  Like others of its genus it comes from its hiding place at sunset, and its note in the distance is exactly like that of the cuckoo, but the sound changes as you approach it.  This bird has a dark brown plumage, spotted white, and differs in many respects from the genus Strix, although very closely allied to it.

15.  AEGOTHELES novae-Hollandiae, Vig.  And HORSF.—­Owlet night Jar.