CHAPTER IV 

 SKELETON 



THE typical Ophidian skull is characterized by 

 a solidly ossified brain-case, with the distinct 

 frontals and the united parietals extending downwards 

 to the basisphenoid, which is large and produced 

 forward into a rostrum extending to the ethmoidal 

 region. The nasal region is less completely ossified, 

 and the paired nasals are often attached only at their 

 base. The occipital condyle is either trilobate and 

 formed by the basioccipital and the exoccipitals, or a 

 simple knob formed by the basioccipital ; the supra- 

 occipital is excluded from the foramen magnum. 

 The basioccipital may bear a strong, curved ventral 

 process or hypapophysis (in the Vipers). 



The prefrontal is situated, on each side, between 

 the frontal and the maxillary, and may or may not 

 be in contact with the nasal ; the postfrontal, usually 

 present, borders the orbit behind, rarely also above, 

 and in the Pythons a supraorbital is intercalated 

 between it and the prefrontal. 



The premaxillary is single and small, and as a 

 rule connected with the maxillary only by ligament. 

 The paired vomer is narrow. The palatine and 



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