1870.] MR. HUDSON ON THE BIRDS OF BUENOS AYRES. 547 
to contain a large proportion of coleopterous insects. I think it 
very probable that the vast unexplored regions lying between the 
grassy pampas and the Andes will be found to be the native country 
of these birds. I haver never met here with any specimens of the 
Tenioptera nengeta. 
** To see the webs of the Gossamer-Spiders floating in the air is 
here an exceedingly common thing. These little aéronauts are so nu- 
merous that on any still day in warm weather, if one sits down on 
the grass, he will observe numbers of them briskly moving about, 
while some, running to the point of a blade or leaf, suddenly dart 
out their invisible lines and float off. I recollect once, several years 
ago, the sky was for several days full of white masses composed of 
these floating webs. But this afternoon, while I was out shooting, 
these Spiders and their webs presented an appearance that was alto- 
gether new to me. Walking along a stream I observed skirting the 
edge of the low wet ground on the opposite side a broad white line. 
This I discovered to be caused by the quantities of gossamer that 
almost completely veiled the grass and thistles under it. This zone 
of gossamer was about twenty yards wide; and outside of it only a 
few scattered webs were visible. I did not ascertain its length, but 
followed it about two miles without finding its end. I enclose a 
small strip of the webs, which could be easily peeled off every object 
presenting a smooth surface. I observed many of the Spiders ; in- 
deed so numerous were they that they continually baulked each 
other in their attempts to rise in the air. There being a breeze 
blowing, as soon as one threw out his web it would be entangled in 
that of another. Both Spiders would immediately seem to know the 
cause of the trouble, for they would run angrily together, each trying 
to drive the other off. There appeared to be at least three different 
species of Spider. One of these hada round scarlet body ; another, 
of a velvet-black, had a square large corslet and small pointed abdo- 
men. But the greatest number were of the third kind; they were 
all shades of olive colour, from pale green to greenish black, and of 
various sizes, the largest being in body a quarter of an inch long. 
These Spiders could not have been brought by the wind, as the zone of 
webs followed the windings of the stream, but had probably bred 
in the low ground along its margin and had now gathered on its 
edge ready to migrate. 
“27th. On the 25th I went to visit the Spiders I have spoken 
about, fully expecting they would be gone, as we have had wind and 
rain since I first saw them. To my surprise they were vastly in- 
creased in number; on the tops of cardoons they literally were 
in heaps. Most of them were large and of the olive-coloured species, 
and were floating off in great numbers, the day being calm. I 
noticed another kind, of a pale slate-coloured body elegantly striped 
with black, and pink legs. On the 26th I went again to see them ; 
and the whole army of Spiders, save a few solitary stragglers, had 
disappeared. “* Very trulv yours, 
«“WitirAm H. Hupson.” 
