54 



ANATOMY OF VERTEBRATES. 



python a large, vertically oblong, but short diapophysis extends 

 from the fore part of the side of the centrum obliquely backward : 



it is covered by the ar- 

 ticular surface for the 

 rib, is convex lengthwise 

 and convex vertically 

 at its upper half, but 

 slightly concave at its 

 lower half. In the 

 rattlesnake the diapo- 

 physis devclopes a small, 

 circumscribed, articular, 

 tubercle, ib. d, for the 

 ' vertebral rib ' or pleur- 

 ajjophysis, pi; a parapo- 

 physis,^', extends down- 

 ward and forward below 

 the level of the cen- 

 trum ; the anterior zy- 

 gapophysis, z, is sup- 

 ported by a process, 

 ib. d" , from the upper 

 end of the diapoijhysis. 

 The base of the neural 

 arch swells outward 

 from its confluence with 

 the centrum, and de- 

 vclopes from each angle 

 a transversely-elongated 

 zygapophysis ; that from 

 the anterior angle, z, 

 looking upward, that 

 from the posterior angle, 

 r', downward ; both sur- 

 faces being flat, and 

 almost horizontal, as in 

 the Batrachians. The 

 neural canal is narrow ; 

 the neural spine, na, is of 

 moderate height, about 

 equal to its antoro-pos- 

 terior extent; it is compressed and tnuicate. A wedge-shaped 

 process, ' zygosphcne,' zs, is developed from the fore part of the 



skeleton of the colii'a {Naija tripihli,nis) 



