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. 



The largest aquatic order is that of the Limicolaa 

 ■ — 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 



