parapophysis, and by its elongated tubercle to the diapophysis, completing the 

 lateral canal or ' foramen for the vertebral artery.' Hunterian. 



24. A typical vertebra of a Reptile the third dorsal of a Crocodile, in which the 



pleurapophyses are elongated, forming ' vertebral ribs,' and the haemal arch is 

 completed by the haemapophyses (ossified costal cartilages, or sternal ribs) and 

 haemal spine (sternum). The neurapophyses have coalesced with each other 

 and with the neural spine, but articulate with the centrum by suture. The 

 head of the rib here joins a notch upon the largely-developed diapophysis ; the 

 tubercle of the rib still articulates with the end of that process. The parapo- 

 physis is suppressed : the hypapophysis (hp) is retained. 



Prepared by Prof. Owen. 



25. An anterior caudal vertebra of a Crocodile. The pleurapophyses are reduced to 



the proportions they presented in the cervical vertebra, and are simplified in 

 form, being mere flattened laminae articulated by suture to the extremities of 

 short diapophyses. The haemapophyses articulate to the under surface of the 

 centrum, and coalesce with each other and with the haemal spine at their 

 opposite ends. Both parapophyses and hypapophyses are suppressed. 



Hunterian. 



26. A vertebra from the tail of a Serpent (Python). All the parts have coalesced into 



one bone : the pleurapophyses appear as short deflected extremities of long di- 

 apophyses : no haemapophyses are developed in any part of the body of the 

 serpent, but their place is here taken by a pair of exogenous hypapophyses, 

 and consequently the haemal canal is open below. The anterior articular sur- 

 face of the centrum is concave, the posterior one convex. Purchased. 



27. The vertebra of a Bird the lower cervical one of a Pelican (Pelecanus Onocrota- 



lus). The anterior articular surface of the centrum is convex vertically, con- 

 cave transversely ; the posterior surface is concave and convex in the reverse 

 directions : this interlocking articulation of the vertebral bodies is characteristic 

 of the class of Birds. All the parts of this vertebra have coalesced into one 

 piece, the neurapophyses and spine circumscribing the upper or neural canal, 

 the pleurapophyses completing with the diapophyses and parapophyses the 



