Shull and Bones of the Trunk of Common Fowl. 27 



its missing cervical vertebrae may be said to correspond to one of 

 the two which come third and fourth in order in the neck of the 

 Fowl. The other seems to correspond to one of the four vertebrae 

 bearing- hypapophyses which interpose themselves in the Fowl 

 between the first dorsal vertebra and the last cervical with a demi- 

 canal on its under surface, as well because this portion of the neck 

 which corresponds to the lower portion of the italic S shaped curve 

 which this region describes in Birds is markedly shorter in the 

 Pigeon than in the Fowl,, as for other reasons relating to number 

 and shape. 



The neural spines are not greatly developed anywhere in the 

 cervical region, and least in its central portion, where the hypapo- 

 physes are also wanting, and their place taken l)y the carotid demi- 

 canal. In the dorsal region in the Fowl, the second, third, 

 fourth, and fifth vertebrae are anchylosed to each other by their 

 bodies, arches, and outgrowths, making thus a rigid central bar 

 with one free vertebra interposed, both anteriorly between itself 

 and the cervical series, and posteriorly between itself and the last 

 dorsal vertebra which is anchylosed to the sacral series. In the 

 Pigeon and many of its allies it is only the third, fourth, and fifth 

 vertebrae which have thus coalesced, the second remaining free. In 

 the Fowl the second, third, fourth, and fifth ribs carry each an epi- 

 pleural appendage, the processus uncinatus, as they do also in the 

 Pigeon, in which bird, however, the sixth also is similarly armed, 

 which is not the case in the Common Fowl. In both birds alike, 

 four only of the seven ribs articulate by means of the sternal ribs 

 with the sternum. Each of these sternal ribs has its upper or cos- 

 tal articular surface elongated anteroposteriorly, and its lower or 

 sternal elongated transversely, and more or less distinctly bifacetted, 

 to correspond to the more or less distinctly bifacetted articular sur- 

 face of the costal border in the sternum. The last sternal rib artic- 

 ulates not with the sternum but with the sternal rib next in front 

 of it, and both of these haemapophysial elements, and especially the 

 more posteriorly-placed one, are at their upper end much broader 

 than any of the other ribs. The similarly-expanded, or ' pedatc ' 

 extremity of the external hyposternal process overlaps the pos- 

 terior sternal ribs, and shows, as does also the shape of the articu- 

 lations of the ribs, that little, if any, transverse dilation of the 

 thorax is possible in these creatures, and that the act of respiration 



