24 Mr. Selby on a nexo Species of Swan. 



the Hooper, on the contrary, the tracheal tube does not enter the tho- 

 rax, but, a little in advance, is joined to the inferior larynx, which is 

 placed obliquely upon the anterior ridge of the sternum, or where the 

 clavicles are articulated with it, as shewn in PI. VI. fig. 2. This bone of 

 divarication is very much compressed, ( PI. VI. fig. 6.) and, as I have 

 before stated, not so much as half the diameter of that of the lesser 

 species ; in shape it very closely resembles the mouth piece of the bas- 

 soon, and the trachea, where it is attached to it, is greatly contracted 

 and somewhat compressed (PI. VI. fig. 7)- This difference of formation, 

 at such a peculiar part of the windpipe in the two species, very satisfacto- 

 rily accounts for the dissimilarity of their note, as noticed in the flock at 

 Sweet-hope Lough. In the form and size of the bronchi of the two 

 species, there is also a marked and very essential difference, those of the 

 new kind being very short, and scarcely measuring two inches in length 

 (PI. V. figs. 1 & 3) ; whereas the Hooper has them generally more than 

 three inches long, with a diameter at the swollen part more than double 

 that of the C. BewkJcii as shewn in PI. VI. fig. 2. 



It must also be noted that the calibre of the whole of the trachea of 

 the new kind is considerably inferior to that of the Hooper, and that 

 the number of ribs differ in the two species, the Hooper having ten, 

 the new species only nine on each side. Such, and I may add so 

 marked, are the distinctions which present themselves upon a review 

 and comparison of the parts of the two birds, and I think I may con- 

 fidently add, that they are of sufficient magnitude to warrant Mr. 

 Wingate's conclusions. Indeed they are as great as can well sub- 

 sist between species of the same genus, for if greater, they would, ac- 

 cording to the views of systematic arrangement entertained by natural- 

 ists of the present day, entitle the subject not merely to a specific but 

 a generic distinction. In all the specimens of the new kind (and a 

 considerable number have been examined), the peculiarities which dis- 

 tinguish them from the Hooper, are the same ; they are all greatly 

 inferior in size, all vary in the form of the bill, proportion of the wings, 

 the shape of the tail, and the number of the rectrices ; in all, the con- 

 volutions of the windpipe where it has attained its full developement. 



