i SS 3 - ] Barrows on Birds of the Lower Uruguay. 1 37 
Not one of them has bright colored plumage, if we except 
the sulphur-yellow under-parts in two species ( Sisopygis and 
Machetornis ) and a half concealed crown-patch of orange-red in 
Machetornis ; yet almost every one possesses some character- 
istic of form, color, or habit, which makes it conspicuous even 
to the casual observer. Well-defined areas of black and white 
mark several species, while peculiarly developed outer tail- 
feathers, or remarkable eye-lids characterize two others. 
48. Agriornis maritima ( Lafr . et d’Ord.). — Only met 
with a few times in the gorges of the Sierra de la Ventana, 
where it was sometimes seen perched motionless upon a great 
block of gneiss, or darting suddenly out after a passing insect. 
49. Teenioptera nengeta (Linn.). Alcahuete (a word 
which unfortunately has no precise equivalent in English, but 
which, as it refers to the remarkable vigilance and quickness of 
the bird, may be very liberally translated sentinel.) 
These birds and the following species ( T. coronata) appear 
at Concepcion at the first appearance of cold weather, and remain 
until spring opens. They are most abundant between April 
1 and August 15, but possibly a few of the present species 
remain through the summer, as a single one was taken September 
8, and another on February 11. 
They are commonly seen perched on fences or the tops of 
bushes or trees in open ground, frequently making sallies for 
winged insects, or dropping to the ground to catch a grasshopper 
or worm. When shot at while perched and watching you, they 
almost invariably leave the perch at the flash, pitching forward 
and downward and usually evading the shot even at short range. 
Several times I have secured them by shooting about a foot 
below and two feet in front of them as they sat, but they do not 
always fly in this direction. Much the surest way of dropping 
them is to walk up till they fly, and then shoot, as they seldom 
dodge while on the wing. The rapidity of their flight when 
frightened, or when quarreling, is simply astonishing. I have 
seen one chase another for three or four minutes, doubling, turn- 
ing, twisting and shooting, now brushing the grass and now 
rising to a height of at least two or three hundred feet, and all 
the movements so rapid that the eye could scarcely follow them ; 
and at the end of it each would go back to the top of his own 
chosen weed-stalk, apparently without a feather ruffled. 
