STENEOSAUKUS. 



97 



The number of dorsal and lumbar vertebrae is not quite certain, but, judging from 

 several skeletons which are probably complete in this region, there would seem to have 

 been 12-13 dorsals (rib-bearing) and two lumbars. 



The dorsal vertebrae (text-figs. 36, 37) differ from one another in the various species 

 to a less decree than do the cervicals and caudals, though in them also the relative 

 length of the centrum is correlated with the greater or less elongation of the skull. 

 The centra are strongly constricted in the middle, both the ventral and lateral surfaces 

 being concave in a longitudinal direction ; at the rim of the articular surfaces they are 

 thrown into numerous small plications which may become strong rugosities, especially 



Dorsal vertebrae of Steneosawas leexlsi : A, middle dorsal from above ; C, the same from left side : 



B, anterior dorsal from left side. (R. 3S06, | nat. size.) 



a.z., anterior zygapophysis ; dp., diapophysial process ; n.sp., neural spine ; pp., parapophysial process 



p.z., posterior zygapophysis ; t.p., transverse process. 



on the postero-ventral border. The ventral face is sometimes slightly flattened, but in 

 no case is there any hsemapophysial ridge or process. The articular ends are gently 

 concave, at least in the middle ; in some cases towards the rim they may be flattened 

 or even a little convex. The vertical diameter is a little greater than the transverse, 

 this difference being in some cases a little more marked on the posterior than on the 

 anterior face; usually the upper border beneath the neural canal is flattened or slightly 

 concave. 



FAST II. o 



