Cape San Antonio, Buenos Ayres. 33 
raspberry -like ova (as I take them to be)*, and lined with the 
dry thread or fibre from the interior of the same plant. The 
whole structure is about four inches in length (outside mea- 
surement), and one and a half in diameter, the sides being 
barely one quarter of an inch thick, and the bottom half an 
inch. There is not a single straggling fragment of material 
about it ; itis very light and delicate ; and yet it may be tossed 
about any way, or even packed among empty Swan-eggs 
without receiving damage—the neatest nest we have, in 
short. It is rather difficult to find in the swamps, being so 
small, and placed low down, while the rider is raised just as 
high again in the saddle ; besides which, it harmonizes admi- 
rably in colour with the rushes and reeds amongst which it 
is situated. 
The general clutch of eggs is two; at least I never took 
more, and have found even that number considerably incu- 
bated. They are of a pale cream-colour, which darkens 
toward the blunt end, and occasionally merges into a faint 
brownish ring there. The average measurement is about 
25 18 
40 * 40: 
o/7. CYGNUS NIGRICOLLIS. ‘‘ Cisne.’’ 
As there are a great many swamps and fens here, it is but 
natural that all the waterfowl should be represented in ex- 
traordinary numbers ; and accordingly even Swans are nearly 
as abundant with us as Ducks are in other districts. I have 
counted about two hundred on one small lagoon in a swamp ; 
and the latter is but one in a whole network of swamps and 
watercourses. Another great fen, bordering our land, is 
known as the Cafiada de Cisneros, or Swamp of the Swan- 
neries, an eminently suggestive name for the oologist, one 
which its character well bears out. About the beginning of 
* This is rather a peculiar object, consisting of a number of eggs, each 
about the sixteenth of an inch in diameter, gummed together into a mass 
and attached to some rush or plant in the swamps above the water. The 
shells are raspberry-coloured, and brittle, like glass; the contents are a 
transparent colourless mucilage. They are very common. ‘The only 
change in their appearance is that the eggs sometimes fade in colour, 
SER. IV.—VOL. IV. D 
