'SS3.] Barrows on Birds of the Loiuer Urziguay. I go 



6i. Hapalocercus flaviventris Lafr. et t/'Or^.— Abun- 

 dant in summer in wet marshes and among the rank grass and 

 rushes about ponds and streams. Its rasping notes, energetic 

 movements, and yellow underparts make it quite conspicuous, 

 although one of the smallest species taken. It certainly breeds 

 here, and doubtless also as far south as Carhu^, many individuals 

 being seen near that place in March, 1881, but I was unable to 

 learn anything of its nesting habits. 



62. Serpophaga subcristata ( VieilL) . — This tiny Fly- 

 catcher much resembles in general habits our own Least Y\y- 

 ca.tch.er {Smpidonax minimus) , but its motions and notes are 

 much less energetic. It was noticed only in summer and always 

 among trees or bushes. Nests were taken from October 14 

 until late in November. They were all similar in material and 

 construction, being made of various cottony fibres, wool, and 

 fine hair, and seated among thorny twigs, usually in a fork and 

 at distances from the ground varying from three to fifteen feet. 

 The eggs were commonly three, white, with a bufly tint, and 

 unmarked. 



63. Serpophaga nigricans {VieilL). — During the cool 

 weather — from April to September — this plain but pretty species 

 was found among the rushes of every marsh and stream which 

 was visited, both at Concepcion and further south. It seemed 

 particularly fond of the I'ushes, and among these frequently 

 half a dozen were in sight at once, spreading and flirting their 

 tails and making short sallies for passing insects, always uttering 

 their characteristic chuck, which was the only note heard. 



Very few remain at Concepcion through summer, and those 

 which do are found most often among the interlacing roots and 

 half-fallen bushes along the river margins. The only nest which 

 I found was a bulky structure composed largely of dark, fibrous 

 moss mixed with grass and lined with finer material of the same 

 kind. It was half swung, half seated on a leafless branch which 

 drooped from the roof of one of those cobwebby, natural arbors 

 formed by masses of vines striving to cover up and hide the 

 bushes which they have killed. This nest, with its three white 

 eggs and the parent bird, was secured at Concepcion, December 

 7, 1880. It was close to the undermined bank of the stream 

 where it could only be seen from a boat passing close under the 

 overhanging bushes. 



