U4 Dr. Lath am* j EJfay on the Trachea? or Windpipes of Birds* 



a trifle fmaller towards the bottom: the bony arch, as in others, 

 finiihes the bottom part, and feems as if fumifhed with rings, but 

 they are not moveable as in the reft of the trachea. The orbicular 

 labyrinth is attached to the fide of it; this is not fmooth on the 

 furface as in the Pintail and Wigeon, but univerfally rough, and irre- 

 gularly furrowed with fine indented lines. The oppofite fide runs 

 into a pear fliape, and is placed obliquely, with the pointed end 

 loweft, as in the two laft named birds, but is flatted confiderably on 

 the furface. The bony arch on this fide is fmooth, having no ap- 

 pearance of rings, and is bent at a fmall angle from the trachea^ 

 although it conftitutes a continuance of it : this is the defcription of 

 the organ in a young bird. 



In a fpecimen fomewhat more advanced in age, with which 1 

 was favoured by Mr. Lamb of Reading, the bony labyrinth ap- 

 proaches more to a rounded lhape, and is larger, but ftill retains the 

 rough furface, and the appearance of bony rings on the arch feems 

 Icfs diftinct; — and in an old bird, the drawing of which I was favoured 

 with by Mr. Boys, the labyrinth is not only much larger in fize, but 

 is nearly globular, and the bony arch quite fmooth : yet Mr. Boys 

 obferves, that the labyrinthic part is finely granulated and faintly 

 wrinkled, and the texture firm and bony ; but in this laft circum- 

 ftance it does not differ from the younger ones. As to that figured 

 by Dr. Bloch, in the Berlin Tranfaclions, it feems at firft light too 

 large by many degrees; yet I will not venture to fay that his figure of 

 it is faulty, for in cafe the Mufcovy Ducks ever arrive at twice the 

 fize we ufually fee them in England, which they are faid to do in 

 warm climates, no doubt but the labyrinth will bear its due pro- 

 portion. 



XIX. ANAS 



