brown, crossed by irregular bands of freckled brownish grey and black; the next on each side similar, but the bands narrower and less conspicuous; the two outer ones on each side very dark brown for three parts of the length, the apical portion being white, stained with freckled buff and black on the outer webs; the basal or dark portion crossed by narrow indistinct and irregular bars of deep buff; breast freckled buff, grey and brown, some of the feathers in the centre of the breast largely tipped with buff; abdomen and under tail-coverts deep buff, crossed by narrow regular bands of dark brown; irides blackish brown; bill black; feet and claws reddish brown. The Plate represents a male and a female of the natural size. [Illustration: ACANTHYLIS CAUDACUTA. _J. Gould and H. C. Richter, del^t_ _C. Hullmandel Imp._ ] ACANTHYLIS CAUDACUTA. Australian Spine-tailed Swallow. _Hirundo caudacuta_, Lath. Ind. Orn. Supp., p. 57. sp. 1.—Lath. Gen. Hist., vol. vii. p. 307.—Vieill. 2nde Edit. du Nouv. Dict. d’Hist. Nat., tom. xiv. p. 535; and Ency. Méth. Orn., Part II. p. 531. _Needle-tailed Swallow?_ Lath. Gen. Syn. Supp., vol. ii. p. 307.—Steph. Cont. Shaw’s Gen. Zool., vol. x. p. 133. _Pin-tailed Swallow_, Lath. Gen. Hist., vol. vii. p. 308. _Chætura Australis_, Steph. Cont. Shaw’s Gen. Zool., vol. xiii. p. 76. _Hirundo pacifica_, Lath. Ind. Orn. Supp., p. 58.—Vieill. 2nde Edit. du Nouv. Dict. d’Hist. Nat., tom. xiv. p. 511; and Ency. Méth. Orn., Part II. p. 529. _New Holland Swallow?_ Lath. Gen. Syn. Supp., vol. ii. p. 259.—Steph. Cont. Shaw’s Gen. Zool., vol. x. p. 132.—Lath. Gen. Hist., vol. vii. p. 308. _Chætura macroptera_, Swains. Zool. Ill. 2nd Ser., pl. 42.—Gould, Birds of Australia, Part II. cancelled. This noble species, the largest of the _Hirundinidæ_ yet discovered, is a summer visitant of the eastern portions of Australia, proceeding as far south as Van Diemen’s Land; but its visits to this island are not so regular as to New South Wales, and its stay in these southern latitudes is never protracted. The months of January and February are those in which it has been most frequently observed in Van Diemen’s Land, where it simultaneously appears in large flocks, which after spending a few days disappear as suddenly as they arrived. I am not aware of its having been observed in Western Australia, neither has it occurred in any of the collections formed at Port Essington.