Genus — P ACHY CE PH ALA. 
Pachycephala Vigors, Trans. Linn. Soc. (Lond.), 
Vol. XIV., p. 444, 1825. Type (by original 
designation ) ... ... ... ... ... Muscicapa pectoralis Latham. 
Also spelt — 
Pachycephalus Stephens, in Shaw’s Gen. Zool., Vol. III., pt. n., p. 267, 1826. 
Medium Pachycephaline birds with medium to small bills, long wings, long 
tail and medium legs and feet. 
The above terms must be interpreted in connection with the word 
“ Pachycephaline,” as this group shows many features peculiar to itself, but 
the absolute relationship of the series has not been determined. 
The bill is somewhat laterally compressed, the sides sloping steeply, the 
culmen ridge sharply keeled, the tip with a fine decurved point followed by a 
1a,n iin e notch ; the under mandible fairly deep, the depth of the bill at base 
varying from half to one-third its length. The nostrils are situated in a 
groove at the base of the bill, semi-operculate and almost hidden by projecting 
feathers and bristles. The rictal bristles are strong and prominent. The 
wing has the fourth primary longest, the third and fifth little less and subequal, 
the sixth almost as long, the second shorter than the seventh with the first 
about half the length of the second. In some cases the fourth and fifth appear 
subequal, the third and sixth also about the same length. In other words, the 
tip of the wing is formed by the third to sixth primaries, the secondaries long, 
reaching the ninth primary. The tail is long and emarginate about two-thirds 
the length of the wing. The legs are not very stout, the tarsus showing in 
front half a dozen distinct scutes ; the feet are rather small, the middle toe 
longest but almost equalled by the hind one, the outer longer than the inner. 
This is the type of the large series now known as Thickheads, and the 
different genera included in the series must be circumscribed by colour values, 
otherwise there can be no definition of its limits and many distinct groups will 
be confused. Thus the nestlings of this species are reddish all over, but as 
soon as they leave the nest they lose this and become grey-backed with greyish 
underparts, the throat being speckled. 
I used this genus as an example in a short account entitled “ The Admission 
of Colour-Genera,” published in the Emu , Vol. XV., p. 118, 1915. I there 
stated the paper was a resume of a meeting held by the British Ornithologists’ 
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