X24 Dr. Latham** Ejjfay on the Trachea or Windpipes of Birds, 



XXVII. MERGUS ALBELLUS— The Smew. Tab. xvi. Fig. 3, 4. 



M. crifta dependents, occipite nigro, corpore albo, dorfo tempori- 



bufque nigris. 

 Mergus Albeilus, Linn. Syjl. Nat. i. p. 209. — Ind. Orn. ii. p. 831. 



Rati Syn. Av. p. 135. A. 3. — Brif. Orn. vi. p. 245. t. 24. f. i. 

 Petit Harle huppe, La Piette, Buf. Oif. viii. p. 271. pi. 24. — 



PL Enl. 449. 

 Die weifie Nonne, Befch. der Bed. Nat. Fr. iv. p.. 596. t. 18. f. 7. 

 Die weifie Tauchente, Beck/}. Fog. Deutfch. ii. p. 738. 

 Smew or White Nun, Gen. Syn, vi. p. 428. — Br. Zool. No. 262. — 



Will. Or/y p. 255. t. 64. 



This beautiful bird is confiderably fmaller than the two laft de- 

 fcribed, and the authors above referred to will point it out ihould any 

 one be ignorant of the fpecies- The fize of the trachea is fmalleft 

 near the upper part, but enlarges as it approaches towards the 

 middle; from whence to the bottom part it continues of nearly equal 

 dimenfions, the texture con fifting of bony rings, with fcarcely any 

 cartilage appearing to intervene. At the bottom part is a bony 

 cavity as in the others, but of a different form, being much fmaller 

 in proportion, and differing in fhape, the greater expanfe being from 

 fide to fide, whereas in the others it is almoft upwards and down- 

 wards : on one fide is a round hole covered by a drum-like mem- 

 brane, and on the oppofite an oval fmooth hollow bone uniting with 

 it - r from the bottom of thefe arife the bronchia. 



In this, as in the former, two fpecies have been created out of one, 



and owing precifely to the fame caufe ; which is, that of the 



young male having the female plumage for fome length of time after 



growing to fize. I have detected this fome time fince by the laby- 



1 rinth 



