20 The Naturalist in La Plata. 
graceful variegated ypicaha, fond of social gatherings, 
where the birds perform a dance and make the 
desolate marshes resound with their insane human- 
like voices. A smaller kind, Porphyriops melanops, 
has a night-cry like a burst of shrill hysterical 
laughter, which has won for it the name of * witch ;”° 
while another, Rallus rythyrhynchus, is called 
“little donkey’ from its braying cries. Strange 
eerie voices have all these birds. Of the remaining 
aquatic species, the most important is the spur- 
winged crested screamer; a noble bird as large as 
a swan, yet its favourite pastime is to soar upwards 
until it loses itself to sight in the blue ether, whence 
it pours forth its resounding choral notes, which 
reach the distant earth clarified, and with a rhythmic 
swell and fall as of chiming bells. It also sings by 
night, “ counting the hours,” the gauchos say, and 
where they have congregated together in tens of 
thousands the mighty roar of their combined voices 
produces an astonishingly grand effect. 
he largest aquatic order is that of the Limicole 
—snipes, plover, and their allies—which has about 
twenty-five species. The vociferous spur-winged 
lapwing, the beautiful black and white stilt, a true 
snipe, and a painted snipe, are, strictly speaking, 
the only residents; and it is astonishing to find, 
that, of the five-and-twenty species, at least thirteen 
are visitors from North America, several of them 
having their breeding-places quite away in the 
Arctic regions. ‘This is one of those facts concern- 
ing the annual migration of birds which almost 
stagger belief; for among them are species with 
widely different habits, upland, marsh and sea-shore 
