RED-BREASTED MERGANSER. 4Q1 



of gravel. The inner surface of the oesophagus is very smooth when 

 extended, plicate when contracted, with longitudinal series of mucous 

 crypts with wide apertures, which become more numerous and close 

 toward the proventriculus. The glandules of the latter organ are irregularly 

 distributed, forming a belt 1|- inches in breadth. They are cylindrical, the 

 largest being i inch long, and 1^ twelfths broad. The duodenum, fg, has a 

 diameter of 7^ twelfths, but beyond its curve contracts 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 A\ twelfths. The cceca, 

 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 

 extremity. 



The trachea is 11^ inches long, and is remarkable for a large dilatation 

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

 which the tube becomes % inch in diameter, afterwards enlarges to 4^ 

 twelfths, then continues 4 twelfths, and ends in an enormous dilatation 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 downwards, 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 without 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 through- 

 out, 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. 



Vol. VI. 55 



