130 Mr. J. Graham Kerr on the Avifauna 



52. Machetornis rixosa. (0/;. cit. i. p. 13].) 

 (No. 44, S juv.) 



The commonest of the Tyraimidse on the Pilcomayo. Very 

 ahunclant by the water's margin, wliere they are seen feeding 

 in pairs, each pair having possession of a definite extent of 

 the river's margin for themselves, and violently resenting any 

 intrusion upon it by other birds of their own species. 



53. EUSCARTHMUS MARGARITACEIVENTRIS. (Op. cH. i. 



p. 136.) 



(No. 38, S •) Near Fortin Nueve. April 4th, 1890. 

 Frequent amongst bnish by the river. 



54. PiTANGus BOLiviANUs. {Op. cit. \. p. 147.) 



(No. 93, $ .) Near Fortin Donovan. May 3rd, 1890. 

 Very common. Often seen sitting on the topmost twigs of 

 the trees. Occasionally observed fishing like a Kingfisher. 



55. Pyrocephalus rubineus. (0;;. cit. i. p. 152.) 

 At times very common. 



56. Myiarchus tyrannulus. [Op. cit. i. p. 156.) 



(Nos. GO, 81, S ■) Near Fortin Nueve. April 14th, 

 1890. 



Very common in forest and among trees on river banks. 

 Hops about wdth its crown-feathers elevated as a crest. 



57. Myiarchus ferox. [Op. cit. i. p. 156.) 

 Freqiient, but much less abundant than M. tyrannulus. 



58. Milvulus tyrannus. [Op. cit. i. p. 160.) 



(No. 196, S-) Fortin Page. September 16th, 1890. 

 Very common in spring and summer. 



59. Pachyrhamphus viridis (Vieill.) : Sclater, Cat. B. 

 xiv. p. 338. 



(No. 138, S •) Fortin Page. July 12th, 1890. 



[The single specimen brought home is undoubtedly of this 

 species. It is a well-known South-Brazilian bird, and must 

 now be added to the Argentine avifauna. — P. L. S.] 



