J 74 ELEMENTS OF OBNITHOLOGY. 



each of whicli is called an ilium — one of them abutting against 

 its whole length on either side. 



Looked at on the ventral surface, there is a continuous 

 median bone — made up of the centra of the anchylosed vertebrss 

 — which is narrowest towards the anterior and more posterior 

 parts of the sacrnm, and is somewhat broad and flattened towards 

 its middle from before backwards. Transverse processes pro- 

 ject outwards conspicuously both in front of and behind this 

 median part, on either side of which no such prominences are 

 conspicuous, so that a depression or hollow appears between 

 that median part and the ilia beside it. This hollow receives 

 and shelters a portion of the kidney. 



The most anterior lumbosacral vertebrae show well developed 

 diapophysial (higher) transverse processes, which become gra- 

 dually augmented, from before backwards, by parapophysial 

 (lower) transverse processes joined with them, and all these abut 

 against the ilium. There may be from two to five or more of 

 these vertebrae. (Fig. 149, 1-7.) 



The true sacral vertebras are those without conspicuous para- 

 pophysial transverse processes, though they may be represented 

 by very short blunt processes, whereof one projects from the 

 front and another from the hinder part of the side of each 

 centrum. 



The " diapophyses " are in the form of lateral plates which 

 pass outwards, one from either side of the neural arch, to an- 

 chylose with the ilium against which they abut. There may 

 be from two to five of these vertebrae. 



The uro-caudal vertebrse are plainly distinguishable by their 

 conspicuous slender lateral processes, which are directed out- 

 wards, backwards, and upwards, and the first three or four of 

 them are for a time united by suture * with their centra, so as 

 to seem more or less distinct in nature. They recall to mind 

 the pleurapophysial processes of the cervical vertebrae, which 

 are, for a time, distinct and separate bones. As the latter are 

 termed cervical ribs, these sacral annexed lateral parts may 

 be called sacral ribs. Besides these, the uro-caudals give out 

 plate-like diapophysial processes. The whole series of lateral 

 processes, whereof those just described are the most anterior, 



* A suture is a line indicating the junction of two bones by a more or 

 less extencled apposition of their edges instead of by any other kind of 

 joint. 



