116 Dr. Laruam’s Effay on the Tracheee or Windpipes of Birds. 
bony rim is much ftronger than any other part of it, and is curved 
backwards, taking into its middle one of the dronchie. The other 
fide confitts of a bony box, {welling in the middle, and furrowed by 
feveral tranfverfe bands: from this fprings the other dronchia. 
XX. ANAS FERINA—The Pocuarn. Tab. xiv. Fig. 5, 6. 
A. cinereo-undulata, capite brunneo, fafcia peétorali criffo uro- 
pygioque nigro. ; 
Anas ferina, Linn. Syft. Nat. i. p. 203.—Ind. Orn, ii. p. 862.— 
Raii Syn. Av. p. 143. A. 10.—Brif. Orn. p. 384. pl. 35. f. 1. 
Millouin, Buf O/f. ix. p. 216.—PI. Enl. 803. 
Der Rothhals, Be/ch. der Berl. Nat. Fr. iv. p. 602. t. xvii. f..5, 6. 
Poker, Pochard, Red-headed Wigeon, Gen. Sym. vi. pe §23.-— 
Br. Zool. No. 284.—Will. Orn. p. 367. t. 72. 
The trachea of the Pochard, at firft fight, feems to be fimilar to that 
of the Scaup, but, on inveftigation, will be found to differ confiderably. 
In the firft place, itis full two inches thorter;. it is alfo of very nearly 
the fame dimenfions throughout, or narrowing very little at the 
bottom. The drum-like labyrinth approaches greatly to that of 
the Scaup in texture, but is more round on the upper fide; it is how- 
ever croffed by a {mall bony partition as in that bird—in both cafes, 
as may be fuppofed, by way of {trengthening the membrane which 
covers the cavity. The bony box, of which the other portion of. 
the labyrinth confifts, is fcarcely elevated on this fide, and on the 
other much lefs fo than is feen in the Scaup ; it likewife forms an ob- 
tufe angle with the reft of the trachea, but in the Scaup it does not 
deviate from a continuation of a ftraight line, although forming a 
confiderable enlargement. __ 
XXI. ANAS 
