VERTEBRAL COLUMN 



73 



concave from side to side. The lateral part is an oval, raised, articular 

 surface, which is more or less concave from the cephalic to the caudal 

 end and convex transversely. It faces ventrally and slightly laterally, 

 and fits over the corresponding raised facet on the body of the rib 

 known as the tubercle. The caudal border also consists of two parts. 

 The medial part is very short transversely, is deeply emarginate, and 

 its medial end is continuous with the dorsal edge of the lateral surface 

 of the body. The lateral part is directed from the medial part toward 

 the head as well as laterally, and is the caudal part of the lateral 

 margin of the facet on the ventral surface. 



The laminse (Fig. 49) taken together have a cephalo-caudal 



FIG. 49. 



Spine. 



Lamina. 



Transverse Process. 



Cephalic Articular Surface. 

 THORACIC VERTEBRA, DORSAL ASPECT. 



diameter twice as great as the transverse diameter. At the cephalic 

 end they are almost parallel to the dorsal surface of the body for a, 

 short distance, but in their caudal part they slope dorsally and toward 

 the tail and project far beyond the body. 



The spinous process rises from the caudal half of the dorsal sur- 

 face and is directed toward the tail, and dorsally. Its dorse-ventral 

 length is twice as great as the cephalo-caudal diameter of the body ; and 

 it is compressed laterally and pointed at the end, which is sometimes 

 bent slightly in a caudal direction. In well-developed vertebrae, on 

 each lateral surface of the spinous process, not far from the tip, is a 

 distinct tubercle for muscular attachment. 



The cephalic edge of the lamina? presents a dee}), median, semi- 

 circular emargination. On each side of this emargination the edge 

 is slightly prolonged on the cephalic articular process. The dorsal 

 surface of this prolongation, as well as the dorsal surface along the 



