COMMON' MERGANSER. 163 



The trachea of the male is very long ; it is com- 

 posed, immediately beneath the throat, of cylindric 

 rings : about two inches down it is suddenly en- 

 larged into a broad and depressed expansion, com- 

 posed of alternate rings ; it is then again contracted, 

 and the rings become cylindric ; afterwards it is en- 

 larged into a second expansion, but smaller than the 

 first ; the tube at a little distance from the inferior 

 larynx becomes very straight and cylindric : the in- 

 ferior larynx is very large, and of a bony texture ; 

 it is dilated in front, on its left side, and behind: on 

 the right side there is a large elevation formed by 

 three bony keels, which are united on the top, and 

 form three flat surfaces, on which a drum-like mem- 

 brane is stretched ; this part of the larynx is sepa- 

 rated interiorly from the osseous portion on the left 

 by a membranous partition, which is open and loose 

 below. The branchial tubes are placed at some di- 

 stance from each other, that of the right being placed 

 immediately opposite to the pendulous membrane 

 which forms the interior partition. 



There appears to be much difference of opinion 

 respecting the identity of the Goosander and the 

 Dundiver; many ornithologists insisting that they 

 are absolutely distinct species, while others of equal 

 experience pronounce them to be merely the sexes 

 of one species : both parties support their assertions 

 by a reference to the great field of nature, which is 

 equally open to the man of science and to the humble 

 and untutored peasant. It appears, however, that 

 the great contrariety of opinion upon these points 

 amongst the ornithologists of this country has origin- 



