422 



ME. ST. GEORGE MIVART ON THE 



Its neural arch is united by suture to its fellows and to the centrum, and is antero- 

 posteriorly contracted below, so as to have a large intervertebral opening both pre- and 

 postaxial of it. 



The most preaxial part slightly rests on the postaxial extremity of the thirtieth 

 vertebra. 



LATERAL ASPECT OF LUMBAR AND SACRAL VERTEBRA OF AN IMMATURE SPECIMEN 



(I natural size). 



Fig. 59. 



1 . Twenty-uinth (or second lumbar) vertebra ; d', its diapophysis ; s', its neural spine. 2. Thirtieth vertebra. 

 3. Thirty-first vertebra ; p", its posterior parapophysial projection, which concurs with the anterior (and 

 smaller) parapophysial projection (p*) of the next vertebra to form an articular surface for the Uium. 4. 

 Thirty-second vertebra ; p^ an^p'', anterior (preaxial) and posterior (postaxial) parapophysial projections ; 

 the latter concurs with the anterior parapophysial projection {p') of the succeeding vertebra to form an 

 articular surface. 5. Thirty-third vertebra ; p' and p", its parapophysial projections. 6. Thirty-fourth 

 vertebra. 7. Thirty-fifth vertebra. 8. Thirty-sixth (or first sacral) vertebra ; cV, its diapophysis ; 

 ^" '", its rib or capitulum, which has coalesced distaUy with the same parts of the two succeeding vertebrce. 

 9. Thirty-seventh vertebra. 10. Thirty-eighth vertebra. 11. Thirty-ninth (or first sacro-caudal) ver- 

 tebra ; dp", its conjoined dia- and parapophysis. 12. Fortieth (or second sacro-caudal) vertebra. 



The diapophysis is inclined like that of the last vertebra, but has a flattened surface 

 at its extremity ; it is quite separate from the parapophysis, which is formed by the 

 ventral part of the neural arch, and ofi'ers a rounded, flat, articular surface (fig. 59) to 

 the ilium. This surface is very slightly reinforced by minute adjacent portions of the 

 centra of this and the precedmg vertebra. 



The side of the centrum at its postaxial part exhibits a small neural foramen near its 

 dorsal border and in front of a large parapophysial surface (fig. 59,^^'), which this 

 part of the centrum contributes towards the proper parapophysial surface of the next 

 vertebra. 



The Thirty-second Vertebra. 

 This vertebra (figs. 59, 60, & 61, 4] has a spinous process at its maximum of deve- 

 lopment and anchylosed to the adjacent spines. 



