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XIII. On some Points in the Anatomy of the Steamer Duck (Micropterus cinereus). 
By Rosert O. Cunninenam, ID., F.LS., CMZS., Professor of Natural 
History, Queen’s College, Belfast. 
Read March 21st, 1871. 
[Puates LVIII. to LXII.] 
THE remarkable bird the structure of which forms the subject of the following few 
observations has been known for a long period to navigators in the stormy waters girdling 
the southern extremity of South America, the peculiar nature of certain of its habits 
readily arresting the attention of the most careless observer. As I have pointed out in 
my recently published volume on the Natural History of the Strait of Magellan, it was 
observed in that region in 1582 by the celebrated Pedro Sarmiento, who has given a 
short but unmistakable description of it in the narrative of his voyage. In the follow- 
ing century it appears to have been noticed by Wood; and about a hundred years later 
it is mentioned by Pernetty, Byron, Cook, and others, who bestowed on it the cognomen 
of the ‘‘ Race-horse Duck.” Between forty and fifty years ago Captain King, who met 
with it abundantly in the course of his survey in the Strait, suggested for it the greatly 
preferable title of Steamer Duck, on account of its movements when swimming present- 
ing a strong resemblance to those of a paddle-wheel steamer. 
Latham was, if I am not mistaken, the earliest naturalist to bestow on it a scientific 
appellation, denominating it Anas brachyptera, for which Quoy and Gaimard substituted 
the name by which it is now generally known, i. e. Micropterus cinereus. King having 
observed that certain Steamer Ducks were possessed of volant powers, while others 
appeared to be incapable of flight, believed that he had recognized two distinct species 
of the genus Micropterus, which were in addition distinguishable both in size and 
in plumage. The flying birds he designated by the specific name of patachonicus, 
while for the non-yolant individuals he retained that of brachypterus'. In the summer 
of 1866, shortly before my departure for the Strait of Magallan, I was requested by 
Prof. Newton to endeavour to ascertain whether this view was correct, or the contrary ; 
and as in the course of three seasons spent in the Strait and on the western coast of 
Patagonia I had many opportunities of observing the bird, I at length succeeded in 
satisfying myself pretty thoroughly on the point, the examination of numerous speci- 
mens having convinced me that there is but one species of Steamer Duck, and, further, 
that the flying birds are adolescent individuals of the non-volant form. My principal 
reasons for this conclusion are, that the flying and flightless birds associate together, 
that the former are smaller in size than the latter, and that I have invariably found the 
1 Proe. Zool. Soc. 1830-1, p. 15, 
VOL. VI.—PaRT vil. November, 1871. 4a 
