m 



Order OPHIDIA. 



Family Conttrictoret. 



Genus Python. 



tin?. The skeleton of the Tiger Boa (Python tigrit). 



It measures 1 1 feet 2 inches in length. It has 74 anterior vertebrae, with hypapophyse* 

 or inferior spines from the body of the vertebra ; 1 79 vertebne bearing moveable ribs, but no 

 hypapophyses ; and 38 caudal vertebne, all of which have hypapopbyses, and mostly in pain. 

 The ribs commence at the third vertebra: they are 'pleurapophyses' or consist of the 

 vertebral portion only, and terminate freely at the opposite extremity, where, in the recent 

 animal, they support short cartilaginous luemapophyies connected with the large, thick, 

 abdominal scutes, and, in connection with their elevation and depression, aid, like limb*, 

 in locomotion. There is no sternum. 



AnchylosU has occurred between the Mwh and N!th vertebra- . The 166th and the 167th 

 vertebra- have been more completely and abnormally blended together, so as to seem but one 

 vertebra on the left side, where that half of the neural arch and spine have completely coa- 

 whilst on the right side each vertebra supports its own rib. A similar abnormality 

 i between the 184th and 185th vertebrae. The first caudal vertebra has free pleurapo- 

 physes, which are bifurcate, the upper prong being the shortest : in the second caudal the 

 left pleurapophysis is free, the right one anchylosed to the diapophysis ; the forks are of equal 

 length in this and the two following : in the fifth caudal the upper prong is again shorter, 

 and in the sixth is reduced to a mere tubercle : here the hypapophyses begin to lengthen 

 and bifurcate, and progressively increase to the sixteenth caudal, and thence gradually 

 diminish. The neural canal, with the neural arch, its spine and iygapophyse, maintain 

 their normal characters to the penultimate vertebra, and the spinal cord continues undivided 

 or unresolved into nervous fasciculi to the same extent. 



Purchaud. 



603. A considerable portion of the spinal column, including 156 vertebra;, wantiug 

 the ribs, of a large Python from Jessore. 



The characteristics of the vertebne of the typical Ophidian Reptiles may be well studied in 

 this specimen. In the Pythons, as in other known Opkidia, all the autogenous elements, 

 except the pleurapophyses, coalesce with one another in the vertebne of the trunk ; and the 

 l>leurapopbyses also become anchylosed to the diapophyses m those of the tail. There is no 

 trace of suture between the neural arch and centrum. The outer substance of the vertebra 

 is compact, with a smooth or polished surface. The vertebne are ' proralian,' that is, they 

 are articulated together by ball-and-socket joints, the socket being on the fore part of the 

 centrum, where it forms a deep cup with its rim sharply defined ; the cavity looking not 

 directly forwards, but a little downwards, from the greater prominence of the upper border : 



