RED-BREASTED MERGANSER, 99 



cal, the largest being ^ inch long, and 1^ twelfth broad. The duo- 

 denum, fg, has a diameter of 7^ twelfths, but beyond its curve con- 

 tracts to 3^ twelfths. The intestine is convoluted into numerous 

 folds ; its length is 5 feet 2 inches, its diameter about 3 twelfths ; 

 but that of the rectum 4^ twelfths. The coeca, Fig. 2, which come 

 off at the distance of 4 inches from the extremity, are 11 twelfths 

 long, 2| twelfths in their greatest diameter, and obtuse at their ex- 

 tremity. 



The trachea is W\ inches long, and is remarkable for a large dila- 

 tation above the middle, 2 inches in length and 11 twelfths in breadth, 

 below which the tube becomes \ inch in diameter, afterwards enlarges 

 to 4 1 twelfths, then continues 4 twelfths, and ends in an enormous di- 

 latation of an irregular form, of which the greatest diameter is 2 inches. 

 It is composed of a bony frame, with two lateral membranous spaces. 

 The rings of the trachea, 152 in number, are broad and firmly ossified, 

 but about 30 at the lower part are very narrow in their anterior half ; 

 about ten are incorporated with the dilatation ; the contractor muscles 

 are very large, expand over the sides of the dilated part, and continue 

 dovmwards, becoming narrower, and ending at the commencement of 

 the tympanum. There is a pair of very large cleido-tracheal muscles, 

 and another of sterno-tracheal ; but there are no inferior laryngeal 

 muscles properly so called, the slip from the contractor ending with- 

 out reaching the last ring. The bronchi come off at the distance of 

 9 twelfths from each other, and are short, but wide, and composed of 

 about 20 half rings. 



In the trachea of a female, which is of a nearly uniform diameter 

 throughout, the number of rings is 150, with 10 united rings, 5 of which 

 extend beyond the bone of divarication, forming the lower larynx, which 

 has no remarkable dilatation. The bronchial half rings are 20. 



