406 SKELETON OF THE FOWL. 



2. The thoracic vertebrae are five in number. The three 



anterior ones are fused together and with the last 

 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 

 transverse 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 vertebrae 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 

 of 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 

 vertebrae 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 vertebrae, 



with broad centra fused together. Their trans- 

 verse processes, which have no ventral elements, 

 are united to form bony plates, which support 

 the ilia along their outer margins. 



Between the bodies of these vertebrae and 

 the ilia are the deep hollows in which lie the 

 middle lobes of the kidneys. 



c. Next come seven vertebrae, 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 



