220 BIRDS OF LA PLATA 
and more powerful me but keeps under the 
diminutive scrubby plants in open, sterile situations. 
About the roots of these wiry little bushes, only 
twelve to eighteen inches high, the bird searches for 
small insects, and when disturbed has a feeble jerky 
flight, which carries it to a distance of about twenty 
yards. It flies with great reluctance, and when 
approached runs swiftly away, leaving a person in 
doubt as to whether he has seen a mouse or a little 
obscure bird. The only note I have heard it utter 
is a faint creaking sound when alarmed or flying. 
HUDSON’S SPINE-TAIL 
Synallaxis hudsoni 
Above fulvous brown, mottled with black, each feather being marked 
with a large black spot; on the upper part of the back the feathers 
are faintly edged with whitish grey; wings blackish, basal halves of 
feathers pale clear brown, forming a transverse bar, the terminal part 
of the feathers slightly edged on the outer webs and tips with ochraceous ; 
tail blackish, the outer pair of rectrices and broad tips of the next 
two pairs on each side very pale brown, the two middle feathers broadly 
margined on both webs with pale greyish brown ; beneath pale ochra- 
ceous brown, with a pale sulphur-yellowish gular spot; flanks with a 
few black marks ; under wing-coverts light cinnamon ; length 7.8 inches. 
Tuts Spine-tail, which Sclater named after me, is 
the Argentine representative of S. humicola of Chili. 
It is common on the pampas, and is sometimes 
called by the gauchos Tiru-riru del campo, on 
account of its resemblance in the upper plumage 
and in language to Anumbius acuticaudatus, which 
is named Tiru-riru in imitation of its call-note. 
