fiU 



WILLIAM R. SMELLIE ON 



• if the back the centra present a more circular outline, but still preserve the 

 flattening under the neural canal. 



Dorsal vertebrae (text-fig. 4, A, B). — In the dorsal vertebrae the neural spines (n.s.) 

 and transverse processes (t.p.) have suffered much from fracture and crushing. In 

 the anterior the transverse processes continue to rise on the neural arch and to 

 increase in length. They terminate in expanded oval facets (r.f.), the long axis of 

 the oval sloping downwards and backwards. These rib facets are strongly convex 

 and have the upper anterior lip refiexed. This is matched by a similar structure 

 on the concave articular surfaces of the heads of the dorsal ribs (text-fig. 6, B, C, D). 



A 



B. 



Text-Fig. 4. 



Middle dorsal vertebra (39th) of Apractoclcidus terctipes : A, from right side ; B, from front. 

 (Type specimen V. 1091, \ na k size.) a.z. , anterior zygapophysis ; n.c, neural canal ; 

 n.s., neural spine; p.z., posterior zygapophysis; r.f., facet for rib ; t.p., transverse process. 



In dorsal regions the nutritive foramina, following the rise of the transverse 

 processes, rise on to the sides of the centra. Towards the posterior end of the back 

 the transverse process becomes shorter, more slender, and lower set on the neural 

 arch, and the articular ends of the centra become wholly concave and lack the 

 convexity and reflexion at the margins. 



The sacral vertebra (text-fig. 5, A, B) shows a wide, rough, excavated facet (r.f.) 

 for articulation with the sacral rib (C), borne partly on the centrum and partly on 

 the neural arch. The sacral rib has not been fused to the vertebra, and the head of 

 the rib bears a rough articular surface corresponding to the rib facet (r.f.) on the 

 vertebra, This surface is formed of two surfaces meeting at an angle of about 

 LOO degrees, the upper portion, doubtless, corresponding to that part of the facet 



