524 ANATOMY OF VERTEBRATES. 



with the eleventh of the Human subject. The neural spine is 

 broader and thicker, especially superiorly ; there is but one costal 

 surface on each side ; the diapophyses are reduced in size, the 

 metapophyses equalling them, the body and neural spine increas- 

 ing. The thoracic ribs are longer and thicker, more convex on 

 their inner side, with the subcostal groove not defined, except in 

 two or three of the longest ribs near their vertebral end ; the neck 

 is shorter and thicker than in Man ; the longest rib is one foot four 

 inches in length, — that of the longest rib in an average-sized man 

 being thirteen inches. The manubrium sterni is much broader than 

 in Man (fig. 183), and less deeply excavated for the clavicles ; the 

 three or four sternebers which coalesce to form the ' body ' of the 

 breast-bone have a like character. The cervical vertebras differ 

 most from the Human in the extraordinary length of the spines 

 of the last five vertebras ; that of the fourth cervical is not less 

 than three inches and a half ; the spines of the sixth and seventh 

 cervicals gradually decrease in lengtli and increase in thickness : 

 the spine of the dentata is trihedral, the surfaces being divided 

 by produced sharp ridges : the canal for the vertebral artery de- 

 creases in diameter from the sixth forward to the atlas. The 

 bodies of these vertebrae are longer in proportion to their breadth 

 than in Man, and the lower (pleurapophysial) part of the trans- 

 verse process of the sixth is more suddenly increased in length 

 and breadth, and diverges more from the upper division of the 

 same process. The atlas is narrower than in Man, with a wider 

 neural canal, especially between the condyles, which are smaller 

 than in Man. An obtuse process is developed backward from 

 the part representing the body, which is broader than in Man ; 

 the perforation of the transverse process is smaller, and that pro- 

 cess is narrower, especially vertically; the groove behind the 

 upper articular processes is deeper and narrower. The axis or 

 dentata differs chiefly in the greater size of the neural canal, and 

 in the greater length and less breadth of the neural spine ; the 

 zygapophyses are smaller, the transverse processes are more 

 directly perforated by the arterial foramina, and the diapophyses 

 are more produced. 



In the first lumbar vertebra, fig. 346, 2, the metapophysis is 

 still large and distinct ; the anterior zygapophysis becomes more 

 convex and oblique in position ; the diapophysis is suddenly elon- 

 gated, as compared with that of the corresponding (second) 

 Human lumbar vertebra ; the chief difference is seen in the 

 smaller size of the neural canal which relates to the inferior 

 developement of the lower extremities. The same difference 



