188 ZOOTOMY. 



against the ilia ( 107), rudimentary neural spine, and no 

 hypapophysis. 



27. The three or four sacral vertebrae (s.i s.$), 

 closely resembling the lumbar, but having transverse pro- 

 cesses, in the form of thin flat plates passing outwards from 

 the dorsal ends of their neural arches and abutting against 

 the ilia : in the adult, the transverse processes of succes- 

 sive vertebrae are fused together, the original spaces between 

 them being marked only by two rows of small apertures. 



28. The first caudal vertebra (r.i), like the sacral, 

 but having, in addition to the lamellar transverse processes 

 springing from its arch, a pair of strong outstanding pro- 

 cesses caudal ribs (c.r) from its centrum, which also 

 abut against the ilia : a distinct passage is left between the 

 two processes. 



29. The remaining ankylosed caudal vertebrae, six in 

 number: in these the centrum becomes progressively 

 smaller, and in all but the first of them (second caudal) 

 there is no distinction between rib and transverse process. 



30. In the young bird the sacrum is a continuous carti- 

 lage, in which the constituent vertebrae are only marked by 

 the transverse processes, and by the median ventral ossifi- 

 cations for the centra (Fig. 46). 



VII. In the remainder of the vertebral column, note : 



31. The free caudal vertebrae, each having a short 

 centrum, a well-marked spine, and long, flat, outstanding 

 transverse processes: in the last two there is also a 

 distinct hypapophysis. 



32. The pygostyle or ploughshare bone, an irregular 

 vertical plate of bone, with its axis almost at right angles to 

 that of the free caudal vertebrae : it forms the hinder termi- 

 nation of the vertebral column and supports the uropygium 

 ( 121, p. 209). 



