SYSTEMATIC REVISION OF THE AUSTRALIAN THORNBILLS 93 
The striking russet colour of the upper tail-coverts and 
the greater depth of black tail-band are characters the specific 
worth of which cannot be maintained when a good series of all 
races of pusilla is examined. Specimens from the probable 
area of intergradation with whitlocki are lacking, but those 
from the southern part of the range approach macularia in 
being darker above and on the flanks. One example from 
Wingamin, South Australia, which has been compared with 
the type of A. pyrrliopygia Gould by Dr. Witmer Stone and 
declared similar, closely resembles macularia in its darker 
colouration, particularly the flanks, which are huffy brown, 
and the depth of tail-hand is less than in typical albiventris 
but greater than macularia. 
Individual variation is exemplified in a series of twelve 
birds from Cobbora, New South Wales, close to Dubbo, the 
type locality of albiventris. In some specimens the lower 
under surface, including under tail-coverts, is white except 
for a tinge of pinkish buff on the flanks, and there are various 
stages up to specimens with deeply-coloured flanks, dark olive 
buff to buffy brown, and pinkish buff under tail-coverts. There 
is similar, though not so notable, variation in the colour 
of upper parts, and failure to recognize these differences as 
individual or, in part, the result of worn plumage, has been 
the cause of much confusion. North named those with light, 
almost white, lower under surface albiventris , and Mathews 
named Cobbora specimens with rich coloured under surface 
cobborensis ; those from the south showing an approach to 
macularia in colouration were named hamiltoni (= pyrrlio- 
pygia Gould) of which lingerandi is a pure synonym. Six 
specimens of the same series were listed by Campbell (Emu, 
xxv, p. 262 and 265), three as “ Acanthiza pyrrliopygia Gould” 
and three as “A. albiventris North,” but in the distributional 
maps recently published by that author, only “A. albiventris ” 
is shown as inhabiting that area (Emu, xxxv, p. 324). 
Acanthiza pusilla whitlocki North. 
Acanthiza whitlocki North, Viet. Naturalist, xxvi, 1909, p. 55 ; Lake 
Way, Western Australia. 
Acanthiza pusilla venus Mathews, Nov. Zool., xviii, 1912, p. 348; Venus 
Bay, Eyre Peninsula, South Australia. 
Acanthiza tanami Mathews, ib. p. 349; Tanami, Central Australia. 
Acanthiza pusilla arno Mathews, Aust. Av. Rec., ii, 1912, p. 44; Arno 
Bay, Eyre Peninsula, South Australia. 
Acanthiza pusilla consobrina Mathews, ib. ; Leigh’s Creek, South Aus- 
tralia. 
