SMEW. NATATORES. MERGUS. 387 
face without rising to breathe-—It feeds on fish (which it Food. 
pursues under water), as also on small crustaceze, and insects. 
It is a very shy and vigilant bird, and takes wing with great 
readiness when apprehensive of danger; flying rapidly, and 
supporting it for a long time. ‘The trachea of the male is 
narrow immediately below the glottis, but becomes gradual- 
ly enlarged as it approaches the middle of its course, from 
whence to the lower larynx it is of nearly an equal diameter, 
formed of bony rings, with very little intervening cartilage. 
The labyrinth is not so large in proportion to the size of the 
bird as that of the Goosander, or of the Red-breasted Mer- 
ganser, and differs also in form; its greatest diameter being 
the horizontal one, instead of the perpendicular. The exte- 
rior face of the tympanum has a large rounded orifice, co- 
vered by a thin membrane, as in the Goosander. The fe- 
males and young males of this bird were long considered to 
be a distinct species ; the discovery, however, by Dr Latnam 
and others, of the males of this supposed species possessing 
the precise tracheal organization of the adult male Smew, 
has enabled later writers to correct the error. Mr SrEPHENS 
has separated the Smew from the other Mergansers, on ac- 
count of the comparative shortness of its bill, and the modi- 
fication of the teeth or serratures, which do not point so dis- 
tinctly backward, and are closer set than in the larger spe- 
cies. At the same time, he has retained the Hooded Mer- 
ganser among them, although its bill (taking the size of the 
respective birds into consideration) is nearly as short as that 
of the Smew, and the teeth, in their form and arrangement, 
differ even more from those of the Goosander, &c. than those 
of the latter bird. This arrangement has not, however, been 
adopted by any other ornithologist. 
Pate 59. represents the Male and Female, of the natural 
size. 
Bill and legs deep bluish-grey. On each side of the face, General 
and surrounding the eye, is a large patch of greenish- CH Ae 
Bb2 
