134 ANATID.K. 



black ; the peculiarity of the nostril has been noticed ; the 

 tubercle, even in an old male, of small size ; the irides brown ; 

 the head, neck, and the whole of the plumage pure white ; 

 legs, toes, and intervening membranes slate-grey. 



From the point of the beak to the end of the tail fifty- 

 seven inches. From the carpal joint to the end of the second 

 quill- feather, which is the longest in the wing, twenty-one 

 inches and a half; tarsus four inches; middle toe and nail 

 five inches and three-quarters. 



Its food and habits closely resemble those of the Mute 

 Swan. 



The organ of voice appears, from one that I examined, to 

 be like that of the Mute Swan ; but Mr. Pelerin has found 

 considerable differences in various parts of the head ; the 

 description and measurements were given in a paper publish- 

 ed in the Magazine of Natural History for 1839, page 178, 

 from which the following is an extract. 



The measurement of an adult cranium of each is as fol- 

 lows : — Length, from the tip of the bill to the base of the 

 occipital bone in C. ivimutabilis, six inches and three-eighths; 

 C. olor, six inches and seven-eighths. Height, from the bot- 

 tom of the lower mandible when closed, to the top of the pro- 

 tuberance at the base of the bill, in C. ivwintabih's, one inch 

 and five-eighths ; C. olor, two inches. Height, from the base 

 of the under jaw to the vertex of the head, just behind the or- 

 bit of the eye, in C. immutahilis, two inches and one-eighth ; 

 C. olor, two inches and one-quartei'. In C. rmnuifabilis the bill 

 is rather more flattened, particularly in the middle, between the 

 dertriim, or nail, and the nostrils ; the protuberance at the 

 base of the upper mandible is less developed. In the Polish 

 Swan the cranium is highest at the supra-occipital portion ; 

 in the Mute Swan the cranium is highest at the supra-orbital 

 portion ; but the greatest difference is ])erceptiblc on com- 

 paring the occipital bones ; the upper portion of this bone in 



