The female differs from the male in having the throat and under surface greyish white, the chest being crossed by an obscure mark of greyish brown, and with a line down the centre of each feather. The Plate represents the two sexes of the natural size. [Illustration: PACHYCEPHALA GILBERTII: _Gould_. _J. Gould and H. C. Richter del et lith._ _Hullmandel & Walton Imp._ ] PACHYCEPHALA GILBERTII, _Gould_. Gilbert’s Pachycephala. _Pachycephala Gilbertii_, Gould in Proc. of Zool. Soc., Part XII. p. 107. Although the practice of naming species after individuals is a means by which the names of men eminent for their scientific attainments may be perpetuated to after-ages, I have ever questioned its propriety, and have rarely resorted to it; but in assigning the name of _Gilbertii_ to this new and interesting species, I feel that I am only paying a just compliment to one who has most assiduously assisted me in the laborious investigations required for the production of the present work, and who was the discoverer of the birds forming the subject of this paper. The specimens transmitted to me by Mr. Gilbert are I believe all that have yet been procured. Although the _P. Gilbertii_ is nearly allied to the _P. rufogularis_, it may be readily distinguished by the rufous colouring being confined to the throat, and not ascending upon the forehead and occupying the space between the bill and the eyes as in that species; it is also a smaller bird in all its admeasurements. Gilbert’s Pachycephala is an inhabitant of the interior of Western Australia. The following notes, which are all that is known of its history, accompanied the specimens sent to me:—“This species inhabits the thick brushes of the interior. It is an early breeder, as is proved by my finding a nest with three newly-hatched young birds in the middle of August. The nest was built in the upright fork of a small shrub about four feet from the ground. It was deep, cup-shaped in form, and constructed of dried grasses, and except that it was rather more compactly built, it was very similar to those of the other members of the genus.” I trust that the publication of this species will induce Mr. Burgess, Mr. Drummond and other residents in Western Australia to seek for and investigate its history. To Mr. Drummond, and his son Mr. Johnson Drummond, botanical science is indebted for many valuable discoveries, and that this slight tribute to their labours in that department may induce them to turn their attention to other branches of natural history is my earnest wish. The sexes of the present bird, as will be seen on reference to the accompanying Plate, exhibit a similar difference in colour as in the _P. rufogularis_; the females of both species being very sombre and devoid of any rufous colouring on the throat and breast.