STRUCTURE OF BIRDS. 25 



neck resembles the letter y. The spinous processes, ^, A, are 

 generally very small, unless in the lower vertebrae. The trans- 

 verse are large, directed forw^ards, and have a pointed process, 

 2, ^, analogous to a rib, and aiFording attachment to the muscles 

 of the neck. 



The length of the neck varies exceedingly, being dependent 

 upon the nature of the food. It therefore in land birds, and 

 the waders, bears a proportion to that of the feet ; but in those 

 swimming birds which reach at their food under the water, as 

 the swan, it is greatly elongated, while the feet are short. 

 The number of vertebrae varies from nine in the sparrow to 

 twenty-three in the swan ; but in general it is from twelve to 

 fifteen. 



The dorsal vertebrae, from ^ to a little beyond /, are those 

 forming the region of the back properly so called, and to which 

 the ribs are attached. They vary in number from six to 

 eleven, being generally seven or eight, which is also the num- 

 ber of the ribs. Here it is observed that six of them, from e 

 iof^ are free, with thin projecting spinous processes, while the 

 two posterior are united with the large bone extending back- 

 wards beyond/*. They are generally shorter than the cervical, 

 are not articulated by intervening cartilages ; and in many 

 birds, some of them, generally those nearest the sacrum, are 

 anchylosed. Their bodies are usually much compressed, and 

 the anterior have inferior spinous processes, to which some of 

 the muscles of the neck are attached. The transverse processes 

 are articulated with the ribs, which are also joined to their 

 bodies. 



The vertebrae of the back having to sustain the other parts, 

 and withstand the shock of the muscles, in flying, the reason of 

 their partial anchylosis is easily understood. But such an 

 union is still more requisite in the posterior vertebrae, which 

 have to support the generally more or less horizontal body, in 

 standing and walking, and transfer its weight to the legs, 

 which are articulated far behind the centre of gravity. The 

 lumbar and sacral vertebrae are therefore anchylosed, and more- 

 over united with the pelvis, to form the great mass of bone 

 extending from / to g. These vertebrae, commonly named 



