I zj_0 Barrows on Birds of the Lower Uruguay. [July 
eggs were sometimes spotted. The sexes are precisely alike in 
color, and the young when able to fly differ but slightly in ap- 
pearance from the parents. From the fact that young unable to 
fly were taken in November, I judge that a second brood is not 
infrequently raised. The adults have several of the first pri- 
maries remarkably attenuate. Young birds appear to acquire 
these attenuate primaries only after a complete moult. But I 
took one specimen which showed one or more primaries with 
tips of ordinary shape but with a line apparently worn into the 
vane of the inner web so as to mark out distinctly the attenuate 
tip, and it seemed as if a little more wearing would cut out a 
piece which would leave the primary as in the old bird. 
53. Myiotheretes rufiventris ( Vieil /.). — The largest of 
the family found at Concepcion, where it occurs only in winter. 
It is found in flocks, the individuals of which scatter about the 
ground and resemble our common Robins not a little. I have never 
seen this species alight on a bush or tree, — but as it is not plenty 
at Concepcion, and as there were no trees or bushes in the region 
where it was abundant further south, I will not say that it does 
not often do so. 
54. Alectorurus guira-yetapa ( VieilL). Tijerita real 
(Royal Scissor-tail) . — Only sparingly found at Concepcion, 
and only during warm weather, when it probably breeds. The 
remarkable condition of the outer pair of tail feathers is interest- 
ing. In the male these two feathers reach a length of nearly 
ten inches, the rest of the tail being about three inches in length. 
The vane on the inner side of each is wanting for the first two 
inches and then suddenly develops to a width of nearly two 
inches, which it maintains almost to the tip when it gradually 
narrows. The vane on the outer side of the shaft is only about 
one-quarter of an inch wide, and is folded so tightly against the 
shaft that it is quite inconspicuous. In the only two males of 
this species which I have seen flying, these long feathers seemed 
to be carried folded together beneath the rest of the tail, and 
stretching out behind like a rudder or steering-oar, their vanes 
at right-angles to the plane of the rest of the tail. The only male 
which I took myself was shot at Carhue, April 6, 1881, and had 
not quite completed the summer moult. The chin, throat, and 
sides of head below the eyes were completely feathered. Two 
males, however, were brought to me at Concepcion, October 7, 
