370 LAMELLIROSTRES OF THE ARGENTINE REPUBLIC. [Mar. 5, 



the plumage on the fore side of the neck forms a darker ring under 

 the white throat, between it and the whitish breast. 



All this whitish colour is more yellowish in the winter dress of 

 the males, and nearly of a reddish colour on the breast. 



This bird is very ready to dive, and disappears under water imme- 

 diately on observing the sportsman, not coming again to the surface 

 until some distance off. Owing to the shortness of its wings its 

 power of flight is very limited ; so it adopts the expedient of diving 

 in order to escape its foes. 



All the before-mentioned species of Anatidae are represented in 

 the Public Museum of Buenos Ayres. 



Azara describes two other species, which I have seen, but which 

 have not yet reached my hands. 



These are : — 



23. Anas bicolor, Vieill. ; Azara, Apunt. iii. p. 443. no. 436. 

 Anas coliaris, Merrem, Ersch. & Gruber, Encycl. torn. xxxv. p. 25. 

 This beautiful Duck I occasionally saw on the lagunes near my 



quinta, when I lived at Parana in the year 1859 ; but I never had my 

 gun, and so could not obtain it. It is not common, and lives in 

 society with the other species there. 



24. Anas melanocephala, Vieill. ; Azara, Apunt. iii. p. 447. 

 no. 438. 



Anas atricapilla, Merrem, ibid. p. 26 ; Gill, U. S. N. Astr. Exp. 

 ii. p. 202, pi. 25. 



Of this Duck I have only seen one specimen, which was in the 

 possession of a private collector, who killed it on a lagune in the 

 interior ; it seems to be very rare in our province. The Prince Max. 

 of Wied mentions it as having been obtained from Rio Grande do 

 Sul in Brazil. 



I will close this paper with some remarks on the number of the 

 tail-feathers of the Ducks, which varies in different species. Possess- 

 ing a large number of specimens of Erismatura, I was induced to 

 give this genus a careful examination. 



Erismatura ferruginea has eighteen rigid feathers, the largest 

 number observed by myself in this group of birds ; and a like number 

 was found by Azara in Cairina moschata. 



The long-tailed group of Bafila (B. bahamensis and B. spini- 

 cauda) have sixteen tail-feathers, and Azara mentions that he found 

 the same number in Anas bicolor, as also in Spatula platalea. 



In Sarcidiornis regia, Metopiana peposaca, Mareca chilo'ensis, 

 Bafila viduata, B.fulva, Querquedula brasiliensis, and Q. maculi- 

 rostris I have found fourteen tail-feathers. 



Most of the smaller species have twelve tail-feathers : such are 

 Pterocyanea cyanoptera and the other Querquedula. Azara also 

 gives the same number for Anas melanocephala. 



