THE SMEWS. 51 



with flapping wings, and the air filled with a roar like that of a 

 cataract. The rapid vibrations produc ed in the air by tens of 

 thousands of wings cauld be plainly felt." 



Nest. Placed in a depression of the ground, or in a tuft of 

 grass ; made of weeds, or moss, twigs, and water-plants. 



Eggs. From five to eight in number. They resemble those 

 of the Black Scoter and the Velvet Scoter, but are smaller. 

 Slightly greenish cream-colour. Axis, 2-4 inches; diam., r6. 



THE MERGANSERS. SUB-FAMILY MERGING. 



The members of this Sub-family constitute a small, but very 

 natural group of the Diving Ducks. They have the hind- 

 toe with a very broad lobe, as is usual in this group of the 

 Family Anatida. They have only an ordinary tail, not the 

 stiffened tail of their natural allies, the American Torrent- 

 Ducks (Merganctta\ nor the Old World EHsmatura, but the 

 bill is remarkable, as the lower mandible shows no trace of 

 lamellae ; but it has a series of serrations, like teeth, on its upper 

 edge, and these are also found along the edge of the upper 

 mandible. These look like teeth, but they are not real teeth, 

 as in the case of ancient birds like Archceopteryx and 

 Hesperornis. This is easily proved by an examination of the 

 skull, for, the sheath of the bill being removed, it is seen that 

 the margins of both mandibles are perfectly smooth, and bear 

 no trace of serrations or teeth. 



THE SMEWS. GENUS MERGUS. 



Mergits, Linn. Syst. Nat. i. p. 207 (1766). 



Type, M. albellus, Linn. 



The Smews are represented by a single species, which be- 

 comes, of course, its type. It is easily recognised from the 

 other Mergansers by its short bill, the culmen, or ridge, of 

 which is shorter than the tarsus of the bird. 



Mergus is a Palaearctic genus, the Smew breeding in the 

 high north, and wandering south in winter. 



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