MERGANSERS.
The Mergansers are a well-defined little group of fish-eating Ducks, forming the sub-family Merginæ. They are characterised by their slender, narrow bill, furnished on both upper and lower mandible with saw-like lamellæ or denticulations. The head is always more or less crested; in most other respects they resemble the Diving Ducks, all the species seeking for their food by diving. The sexes differ in colour of plumage, but not, perhaps, to such a marked extent as in some other divisions of the Anatidæ. Six species of Mergansers are known to science, of which four are included in the British list—one as a rare visitor from North America. Of the remaining two species, one inhabits South America, the other the Auckland Islands. The young, as usual, are hatched covered with down, and able soon to follow the female to the water. In their moulting and progress to maturity they resemble preceding species.