Crown of the head, cheeks, throat, upper and under surface brownish black; feathers of the breast obscurely tipped with dull olive; ear-coverts yellow; two centre tail-feathers deep blackish brown, the remainder black at the base and tips, the central portion being in some specimens uniform light lemon-yellow, and in others the same colour blotched with spots and markings of brown; bill in some specimens white, in others blackish brown; feet greyish brown; orbits in some black, in others pink; irides nearly black. I believe the birds with white bills to be immature. The figures are about two-thirds of the natural size. [Illustration: CALYPTORHYNCHUS BAUDINII: _Vig._ _J. Gould and H.C. Richter del et lith._ _Hullmandel & Walton Imp._ ] CALYPTORHYNCHUS BAUDINII, _Vig._ Baudin’s Cockatoo. _Calyptorhynchus Baudinii_, Vig. in Lear’s Ill. Psitt., pl. 6. _Oo-l̏aak_ of the Aborigines of the lowland, and _Ngol-y̏e-nuk_ of the Aborigines of the mountain districts of Western Australia. _White-tailed Black Cockatoo_ of the Colonists. This species, which is a native of Western Australia, is distinguished from all the other known members of the group by its smaller size and by the white markings of its tail-feathers. It belongs to that section of the Black Cockatoos in which a similarity of marking characterizes both sexes, such as _Calyptorhynchus funereus_ and _C. xanthonotus_. Like the other members of the genus it frequents the large forests of _Eucalypti_ and the belts of _Banksiæ_, upon the seeds of which it mainly subsists; occasionally it seeks its food on the ground, when insects, fallen seeds, &c. are equally partaken of; the larvæ of moths and other insects are also extracted by it from the trunks and limbs of such trees as are infested by them. Its flight is heavy and apparently laboured: when on the wing it frequently utters a note very similar to its aboriginal name; at other times when perched on the trees it utters a harsh croaking sound, which is kept up all the time the bird is feeding. It breeds in the holes of the highest white gum-trees, often in the most dense and retired part of the forest. The eggs are generally two in number, of a pure white; their average length being one inch and three-quarters by one inch and three-eighths in breadth. The breeding-season extends over the months of October, November and December. Up to the time of writing this account I have never seen specimens from any other part of Australia than the colony of Swan River, over the whole of which it seems to be equally distributed.