Chap. YIH. DIFFERENCES IN THEIE SKELETONS. 



297 



the skull resembles that of a small goose. In the Hook-billed duck 

 (tig. 3y), these same bones as well as the lower jaw curve down- 

 wards in a most remarkable manner, as represented. In the 

 Labrador duck the premaxillaries are rather broader than in the 

 wild duck ; and in two skulls of this breed the vertical ridges on 

 each side of the supra-occipital bone are very prominent. In the 

 Penguin the premaxillaries are relatively shorter than in the wild 

 duck-, and the inferior points of the paramastoids more prominent. 

 In a Dutch tufted duck, the skull under the enormous tuft was 

 slightly more globular and was perforated by two large apertures ; 

 in this skull the lachrymal bones were produced much further 

 backwards, so as to have a different shape and nearly to touch the 

 post. lat. processes of the frontal bones, thus almost completing the 

 bony orbit of the eye. As the quadrate and pterygoid bones are of 



Fig 39.— Skulls, viewed laterally, reduced to two-thirds of ths natural size. A. Wild Duck, 

 B. Hook-billed Duck. 



such complex shape and stand in relation with so many other 

 bones, I carefully compared them in all the principal breeds ; but 

 excepting in size they presented no difference. 



Vertebrae, and Ribs. — In one skeleton of the Labrador duck there 

 were the usual fifteen cervical vertebrae and the usual nine dorsal 

 vertebrae bearing ribs; in the other skeleton there were fifteen 

 cervical and ten dorsal vetebrse with ribs ; nor, as far as could be 

 judged, was this owing merely to a rib having been developed on 

 the first lumbar vertebra; for in both skeletons the lumbar 

 vertebrae agreed perfectly in number, shape, and size with those of 

 the wild duck. In two skeletons of the Call duck there were 

 14 



