_Bill_ shorter than the head, depressed, broad at the base; _gonys_ straight; curving downwards and slightly notched at the tip; _nostrils_ round, placed at the base of the bill, which is beset with strong bristles; _wings_ lengthened and powerful, first primary short, the third the longest; _tail_ rather short and nearly square; _tarsi_ moderate and feeble; _toes_ feeble, the external toe much longer than the internal one. Three species of this genus inhabit Australia, to which country they are confined. 141. Micrœca macroptera. Vol. II. Pl. 93. _Sylvia leucophœa_, Lath. Gen. Hist. vol. vii. p. 139. 142. Micrœca assimilis, _Gould_. _Micrœca assimilis_, Gould in Proc. of Zool. Soc., Part VIII. p. 172. All the upper surface brown, primaries dark brown; tail brownish black; the tips and the terminal half of the external margins of the two outer feathers white; the three next on each side also tipped with white, the extent of the white becoming less upon each feather as they approach the centre of the tail; the four middle feathers without the white tip; throat, centre of the abdomen and under tail-coverts white, passing into pale brown on the sides of the chest and flanks; irides reddish brown; bill and feet blackish brown. Total length, 4⅝ inches; _bill_, 9/16; _wings_, 3⅜; _tail_, 2⅛; _tarsi_, 9/16. Inhabits Western Australia; and is so nearly allied to the _Micrœca macroptera_, from which it only differs in being much less in size and in having the base of the outer tail-feather brown, that I have not considered it necessary to figure it. 143. Micrœca flavigaster Vol. II. Pl. 94. Genus MONARCHA, _Vig. & Horsf._ Several species of this genus occur in the Indian Islands and two in Australia. They are insectivorous birds, and procure their food by quietly hopping about among the branches of the trees. 144. Monarcha carinata Vol. II. Pl. 95. 145. Monarcha trivirgata Vol. II. Pl. 96. Genus GERYGONE, _Gould_. Generic characters. _Bill_ shorter than the head, swollen, notched at the tip; commissure straight; _nostrils_ basal, lateral, oval; _rictus_ beset with two or three extremely fine and weak bristles; _wings_ moderately long, first quill almost spurious, second long, third, fourth and fifth equal and longest; _tail_ rather short and square; _tarsi_ entire, slender, moderately long; _toes_ extremely short and small, the lateral toes even, and united to the middle one nearly to the first joint; _claws_ much curved. The term _Psilopus_ was originally proposed by me for this genus, but that name having been previously employed, _Gerygone_ was substituted for it.