170 



thoracic series, fourteen follow which bear ribs ; these bear a 

 general resemblance to the eighth, with the following modifica- 

 tions. 



There is a gradual diminution in length of the spinous pro- 

 cesses, and those of the tenth to the thirteenth are the most back- 

 wardly inclined; up to this latter point they are slender and rod- 

 like, or rather bayonet-shaped, but at about the fifteenth they begin 

 to be compressed laterally, as well as to become shorter, wider and 

 more vertical. The spinous process of the last thoracic is nearly 

 as wide as high. 



Their transverse processes are of uniform length till the 

 eighteenth is reached, then they become progressively shorter, till 

 at the twenty- second, the process is represented only by a 

 ridge. That of the eighteenth is the last, to which a 

 rib is fairly articulated, though in the case of the rib-bearing 

 vertebra? which follow, there are ligamentous bands which 

 attach the neck of the rib to the transverse process. Two con- 

 tiguous vertebrae provide the articular surface for the heads of 

 all the ribs, except the first, which has a more extensive articu- 

 lation that will be particularly described, and the last two or 

 three. Each vertebra supplies an equal area in the case of the 

 second and third rib, but, in passing backwards, the articulating 

 surface gradually trespasses more and more on the hindermost of 

 the two contiguous vertebra till, in the last two or tliree, it is 

 furnished by the body of a single bone. 



In the twenty -first or penultimate thoracic vertebra, the posterior 

 zygapophysis becomes more distinctly marked, and the posterior 

 articular surface is on it, rather than on the inside of the lamina?, 

 as in the case of the vertebrae preceding, from the eighth to the 

 twentieth. This surface is also more markedly convex instead of 

 nearly flat, and looks downwards and outwards, instead of nearly 

 directly inwards ; the pair fit into two very concave depressions on 

 the anterior zygapophyses of the last thoracic, which almost meet 

 in the middle line. A similar description applies to the last of the 

 thoracic series. 



Metapophyses are distinct on the penultimate thoracic, and 

 become still more marked on the last. Insignificant rudiments 

 of paired hypopophyses, also, appear on the posterior part of the 

 body of the last one of the series. 



Four lumbar vertebrae follow (PI. VII., fig. 9) having the general 

 type of the last thoracic. Transverse processes, small on the 

 first, become larger in the remainder ; in the last two they are long, 

 point forward, and have their extremities somewhat hooked ven- 

 trally. They spring from the junction of the neural arch with 

 the bodies. The metapophyses, which made their appearance in 

 the hindermost thoracic, become here increasingly developed in 



