360 SKELETON OF THE FOWL 



cervical vertebra ; their centra, arches, and various 

 processes being confluent, and the neural spines and 

 hypapophyses forming continuous dorsal and ventral 

 ridges. 



The fourth thoracic vertebra is free; and the 

 fifth is fused with the first sacral vertebra, its trans- 

 verse processes abutting against and fusing with the 

 ilia. 

 3. The sacrum consists of fourteen or fifteen vertebrae, fused 

 together and supporting the ilia. It may be divided 

 into the following regions. 



a. The three anterior sacral vertebrse are firmly fused 



together, and with the last thoracic vertebra. 

 They have stout transverse processes, which abut 

 against the ilia, and which in the first one or 

 two are single, but in the third are divided into 

 dorsal and ventral portions, the latter being very 

 stout, and projecting directly outwards from the 

 broad centrum. The neural spines of these ver- 

 tebrae are fused to form a vertical crest of bone, 

 which is continuous in front with that of the last 

 thoracic vertebra, and fused along its edge with 

 the dorsal edges of the ilia. 



b. Behind these come four or five shorter vertebree, 



with broad centra fused together. Their trans- 

 verse processes, which have no ventral elements, 

 are firmly connected together to form bony 

 plates, which support the ilia along thein outer 

 margins. 



Between the bodies of these vertebras and the 

 ilia, are the deep hollows in which lie the middle 

 lobes of the kidneys. 



c. Next come seven vertebrse, the centra of which are 



compressed laterally in the anterior ones, and 

 dorso-ventrally in the hindmost two or three. 

 The transverse processes, except in the last, are 

 double ; the dorsal elements fusing to form bony 



