206 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



? Mus. Acad. ]S"at. Sci. Philadelphia, No. 1794. {Pull. Eurcpe.) 



Length of bill along gape, 2G'"'"; from the tip to the fore border of 

 the nostrils 14, and to the anterior angle of the eye 36™". Breadth of 

 the bill at the nostrils, 10™'". Toes with claws: Outer toe 32, middle 

 toe 33, inner toe 27, and hind toe 8""". Tarsus 33"'™. 



Color of the bill, brownish, with whitish nail. Legs yellowish-gray. 



The down on the upper surface has a distinct tinge of brownish on 

 the white ground, this tinge changing into a lighter tone on the under- 

 side of the neck, while it forms a very well defined limit against the 

 white on the rest of the under surface. 



This specimen is admitted to the j^resent species with doubt. Per- 

 haps it may belong to 0. cygrius ; but the proportionately great height 

 of the bill at the base, and the positron of the nostrils parallel to the 

 commissure and not to the culmen, seem to indicate it to be a true 

 ^hewiclcii. 



Bewick's Swan has often been confounded with both the Hooper 

 and 0. columbianus^ and even quite recently doubts about the difference 

 from the first mentioned have been stated; whilst the erroneous identi- 

 fication of columhianUs with hewicMi has caused the impression that the 

 latter is to be found in the Nearctic region. 



When once attention has been drawn to the difference between the 

 adult Hooper and the adult hewicku, it is almost impossible after- 

 wards to make a mistake between them, as one, only from the color 

 of the beak, will be able to distinguish them from each other, apart 

 from the size and structural differences, which will be spoken of later. 

 In the Hooper, the yellow color on the bill and lores embraces really a 

 larger surface than the black, and reaches, even on the jaw, in a pointed 

 angle to under and in front of the nostrils, whilst that in the bewiclcii 

 only embraces about one-third of the surface of the bill aud lores, as also 

 that in the latter ends in a curved line behind the nostrils, without 

 reaching them. On some individuals one sees a very little portion or 

 spot of the yellow, stretching itself on to the skin of the nostrils, where 

 it occasionally is said to extend in a narrow stripe to the hind border of 

 the opening of the nostrils, but on the jaw itself the yellow color does 

 not reach by a long way near the opening of the nostrils. The men- 

 tioned relation concerning the extent of the yellow on the skin of the 

 nostrils I have most frequently observed on specimens from Denmark. 



As is clearly shown by a comparison of the measurements given in 

 Tables Y and VI, the difference in size alone is sufficient to separate the 

 adult birds of both species from each other. 



With regard to the adults there is thus no difficulty. On the con- 

 trary, it is not always so easy to distinguish the young birds of the two 

 species from each other, as in them the given distinctions in the color of 

 the bill and the size do not always hold good. Dr. O. FmscH thinks, 

 after having spoken about the mentioned difficulties, which for him even 



