feather-tracts..... Those birds which exhibit no spaces have the wings rudimentary and useless for the purpose of flight." The Apteryx corresponds to the above dictum in Nitzsch's 'Pterylography.' He further remarks (p. 17), "The causes of the interrupted plumage" are "the weight of the feathers and the bending and movements of the limbs and neck."
In the illustration, feathers of the Spotted Emu of Western Australia (Dromæus irroratus, Bartlett) and Casuarius westermanni (the unique specimen of which was named by Dr. Sclater after the distinguished Director of the Zoological Gardens at Amsterdam) are given, to show their bifid character, which does not appear in the family of the Apterygidee; they have no accessory plume to their feathers. There is a beautiful portrait of DromcBiis irroratus (Trans. Zool. Soc. vol. iv. pi. Ixxvi.) in Dr. Sclater's article on the Struthious birds in the Gardens of the Society; and he says: —
"The feathers of D. irroratus are barred alternately Avith silky white and darkish grey throughout their length, terminating in a black tip margined posteriorly with rufous. Those of D. novæ-hollandiæ are uniformly blackish grey from the base to the extremity, which is black with a broad subterminal band of rufous." This Emu was first described by Mr. Bartlett in 1859.
Casuarius westermanni, Sclater, is figured under the name of C. kaupi (Proc. Zool. Soc. 1872, p. 147, pi. ix.), and is again mentioned (1874, p. 247). Mr. Keulemans has well given the terminal spot in the feather of D. irroratus. Professor Huxley makes the genus Apteryx represent the fifth division of the Ratitse (Proc. Zool. Soc. 1867, p. 423). He states that "the feathers are without any after-shaft, while in Casuarius and Dromæus" they are "as long as the principal shafts."
Mr. W.S. Dallas, in the Proc. Zool. Soc. 1865, p. 267, on the feathers of Dinornis, writes:—"The accessory shaft is of a pale horn-colour, and appears to be nearly cylindrical. The structure of the web is somewhat different from that which occurs in the Emu and the Cassowary." This refers to
