Genus — G ILBERTORNIS. 
Gilbertornis Mathews, Austral Av. Rec., Vol. 
I., pt. 5, p. 110, Dec. 24, 1912. Type (by 
original designation) ... P achy cephala rufogularis G ould. 
As diagnostic of this genus, I wrote : “ Differs from Pachycejphala in its stouter 
bill and longer tail which is square, not forked, and in its proportionately 
much longer and broader first primary of the wing.” 
While structurally this genus disagrees very little with Pachycephala, its 
evolution has been on a distinct plan. The young are grey with striped 
under-surface, quite unlike the young of that genus, and the females 
continue the same style with the loss of the striping only, while the males 
simply add a red throat patch and become red on the abdomen. There 
are two species differing in very slight detail, one larger with a thin sharper 
bill, red lores and more red below; the other with the bill shorter and 
stouter, black lores, and less red below. 
It is suggested here, as in the previous and succeeding cases, direct 
evolution from an ancestral Colluricincloid form has taken place, and that 
when supergenera are established we shall have to take into consideration 
the genera classed about Colluricincla as well as these Pachycephaloid, and 
probably with the elimination of the Eopsaltria-like forms which may class 
alongside the Pcecilodryas series. The only method of establishing such 
groups will be by means of study of the economy of the species as well as 
their oology, embryology, plumage changes, superficial characters, colour 
pattern and internal features, the last named being probably the least 
important as showing the least variation in essentials and the most in 
non-essentials. 
Key to the Species of Gilbertornis. 
Males. — Lores black ; bill small and deep inornatus 
Lores red ; bill longer and shallower ; wing larger . . . rufogularis 
Females of both forms very much alike. 
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