Dr. Latham'/ Fffay on the Trachea or Windpipes of Birds. 115 



'■ 

 XIX. ANAS MARILA— Scaup Duck. Tab. xiv. Fig. 3, 4. 



A. nigra, humeris cinereo-undulatis, abdomine fpeculoque alaVi 



albis. 

 Anas Marila, Linn, Syft. Nat. i. p. ig6.—Ind. Om. ii. p. 853.— 



Rati Syn. p. 142. A. 6. 

 Die Bergente, Befch. der Berl Nat. Fr. iv. p. 602. t. 17. f. 3,4. 

 Scaup Duck, Gen. Syn. vi. p. 500. — Br. Zool. ii. No. 275. pi. 100. 



— Will, Om. p. 365. 



The breadth of the trachea of this fpccies, in the middle, is full 

 half an inch ; it lefTens a trifle towards the top, but diminiihes very 

 considerably as it approaches the bottom, fo as not to measure more 

 than three lines where it joins the labyrinthic part ; the total length 

 is from 7^ to 8 inches. We find the name of labyrinth generally 

 given to this portion of the windpipe of the foregoing Ducks ; and 

 we continue the appellation, although the correfponding part in 

 many may be more aptly compared to a drum, and in courfc the 

 word tympanum might be substituted for that of ampulla; as this part, 

 instead of being globular, prefents a more or lefs flatted furface, 

 covered over with a membrane fimilar to that of a drum-head, and 

 ftretched in the fame manner. This drum-like labyrinth exists on 

 the left fide of the irachea y in refpect to its fituation in the neck of 

 the bird, in the fame manner as the globular labyrinths, and in the 

 Scaup feems to be the moft confpkuous of any that posTefs it. 

 The flatted furface of the labyrinth is for the mod part open, ex- 

 cept round the rim, and has an irregular bony arch crossing it from 

 fide to fide; independent of thefe, the furface is covered with a de- 

 licate fine elaftic membrane ftretched over the surface, o-ivins: the 

 idea of the head of a drum in miniature. The lower part of the 



Q^2 bony 



