ClIAi'. VIII. 



DIFFERENCES IN THEIR SKELETONS. 



283 



common duck ; so that the skull resembles that of a small goose. In 

 the hook-billed duck (fig. 39) these same bones as well as the lower jaw 

 curve downwards 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 pre- 

 maxillaries 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 perfo- 

 rated by two large apertures; in this skull the lachrymal bones were 

 produced much further backwards, so as to have a different shape and to 

 nearly touch the post. lat. processes of the frontal bones, thus almost com- 

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

 are of such complex shape and stand in relation with so many other 

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

 ing in size they presented no difference. 



Vertebrae and Bibs. — 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 vertebrae 

 with ribs ; nor, as far as could be judged, 

 was this owing merely to a rib having 

 been developed on the first lumbar ver- 

 tebra ; 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 fifteen cervical and 

 nine dorsal vertebrae; in a third ske- 

 leton small ribs were attached to the 

 so-called fifteenth cervical vertebra, 

 making ten pairs of ribs ; but these ten 

 ribs do not correspond, or arise from 

 the same vertebrae, with the ten in the 

 above-mentioned Labrador duck. In 

 the Call-duck, which had small ribs 

 attached to the fifteenth cervical ver- 

 tebra, the haemal spines of the thirteenth 

 and fourteenth (cervical) and of the seventeenth (dorsal) vertebras corres- 

 ponded with the spines on the fourteenth, fifteenth, and eighteenth vertebras 

 ot the wild duck : so that each of these vertebras had acquired a structure 

 proper to one posterior to it in position. In the twelfth cervical vertebra of 

 this same Call-duck (fig. 40, B), the two branches of the hasmal spine stand 

 much closer together than in the wild duck (A), and the descending haemal 

 processes are much shortened. In the Penguin duck the neck from its thin- 

 ness and erectness falsely appears (as ascertained by measurement) to be 

 much elongated, but the cervical and dorsal vertebrae present no difference; 

 the posterior dorsal vertebrae, however, are more completely anchylosed to 



Fig. 40. — Cervical Vertebras, of natural 

 size. A. Eighth cervical vertebra of 

 Wild Duck, viewed on hasmal surface. 

 B. Eighth cervical vertebra of Call 

 Duck, viewed as above. C. Twelfth 

 cervical vertebra of Wild Duck, viewed 

 laterally. D. Twelfth cervical vertebra 

 of Aylesbury Duck, viewed laterally. 



