84 MAMMALIAN ANATOMY 



the caudal half of the ventral part of the pedicle and is long and 

 pointed, and projects toward the tail, dorsally and but slightly laterally. 



The caudal articular processes are large and distinct, and their 

 articular surfaces face almost directly laterally. Between the caudal 

 articular process dorsally, the accessory process ventrally, and the 

 pedicle on the cephalic side, is a large semicircular emargination which 

 receives the cephalic articular process and the mammillary process of 

 the twelfth vertebra, and thus increases the strength of the interver- 

 tebral articulation. 



The transverse process, as such, is absent, and the rib articulates 

 only by its head with an entire round facet on the cephalic end of the 

 side of the body. 



The pedicles have greater cephalo-caudal and dorso-ventral diam- 

 eters and are directed more nearly perpendicular to the dorsal surface 

 of the body. In a cross-section of the vertebra the neural canal has 

 a rectangular outline. 



The body is longer and wider than the body of the tenth vertebra. 



The Twelfth Thoracic Vertebra (Figs. 54, 55, 56) differs from the 

 eleventh by its greater size and by the shape and the cephalic incli- 

 nation of the spinous process. The maximum cephalo-caudal length 

 of this vertebra is about equal to the maximum dorso-ventral height. 



Its body is about as wide as the body of the eleventh vertebra, and 

 longer. The costal facet is more caudal. 



The mammillary processes and the cephalic articular processes 

 are larger and longer, and the articular surfaces, which are concave 

 in a dorso-ventral direction, are partly on the lam hue, where they face 

 dorsally, but principally on the processes, where they face medially. 



The accessory processes are stouter, and project as far toward the 

 tail as do the caudal articular processes. The gap between the caudal 

 articular process, the pedicle, and the accessory process is smaller. 



The spinous process occupies the greater part of the median line 

 of the lamina?, and, inclining toward the head and dorsally, rises 

 considerably above the level of the mammillary processes. It is 

 laterally compressed, and its cephalo-caudal diameter is less at the 

 end than it is at the base. The cephalic and caudal borders are 

 slightly emarginate, and, above the base, are almost parallel. The 

 end presents a straight, or slightly arcuate, dorsal border. 



The Thirteenth or last Thoracic Vertebra (Figs. 54, 55, 56) is 



