49 2 PATAGONIAN EXPEDITIONS I ZOOLOGY. 



The change of color to orange or cadmium-yellow in the breeding 

 season is to be looked for, as similar changes in the colors of the bill occur 

 in other allied sea-ducks. 



Adult females of this duck in the collections of the British Museum 

 closely resemble adult males in general color. 



After careful study and examination of the material in the British 

 Museum and in the Museum of the Jardin des Plantes in Paris, especially 

 the birds that Dr. Oustalet regarded as a separate species, it appears that 

 the bird called Micropterus patachonicus by King, which was the name 

 Dr. Oustalet employed for his second species of micropterous duck, is the 

 immature of Tachyeres cinereus, which seems not to attain full adult 

 plumage until at least the second and perhaps the third year of its life ; 

 moreover the first breeding is probably accomplished in the phase of 

 plumage called by Dr. Oustalet M. patachonwis. (Miss. Sci. Cap Horn, 

 Tome VI, pp. B. 112-232, E. Oustalet, 1891.) 



The birds of the year should therefore be described as being much darker 

 than adults, with relatively longer wings and with more washing of brown 

 of a deep shade on both breast and back ; they have a similar white mark- 

 ing on the side of the face in the region back of the eye, and the color of 

 the head and neck does not differ from that of the breast and back, while 

 there is no definite area of reddish cinnamon-brown on the throat. The 

 colors of the bill and feet in these birds are very variable and range from 

 pale yellow to brownish green. 



Young birds in the down are figured in an accompanying plate (PI. I). 

 They have the head, breast and upper parts, as well as the sides and flanks, 

 dull slaty gray, with a brownish tone ; the abdomen and under parts and 

 two spots on the head behind the eye on either side are white or creamy 

 white. 



Geographical Range. Southern South America on both the Atlantic 

 and Pacific coasts, to about 41 south latitude ; Valdivia, Chili, on the 

 Pacific coast and to the Mouth of the Rio Negro, Atlantic coast ; more 

 abundant in the Magellan Straits, Fuegian waters and the Falkland 

 Islands ; Picton and Hermit Islands and the waters near Cape Horn ; 

 common at Chiloe Island. 



The "Steamer Duck" or "Race-Horse Duck" was not taken by the 

 naturalists of the Princeton Expeditions, nor do any of the records kept 



