SM.:U. NATATORES. MERGUS. :)87 



face without rising to breathe. It feeds on fish (which it Food. 

 pursues under water), as also on small crustaceae, 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 LATHAM 

 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 STEPHENS 

 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. 



PLATE 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- ti^n" 1 *' 



