JURASSIC VERTEBRATE FOSSILS. 



487 



In the present specimen tin- most characteristic bones preserved are 

 portions of the sacrum and posterior limbs. The former is represented by 

 the lust three vertebrae with their transverse processes. nc;irl\ complete, and 

 by other fragments. The last sacral vertebra has its centrum moderately 



Fig. 33. — Sacrum of Mantotaurus montaniu Marsh; seenfi Itelow. One-eighth natural size. 



a. first »acral vertebra; b, transverse process, or sacral rib, of first vcricbra ; c, same process of second vertebra ; d, 

 same process of third vertebra; c, same process of fourth vertebra; /, foramen between first and second processes;./ 

 foramen between second and third processes ; /", foramen between third and fourth processes; .-.surface for onion v/ith 

 ilium ; p.last sacral vertebra. 



concave below on each side of the median line, l>ut only near its anterior 

 end can indications of a keel be observed. The next sacral vertebra lias 

 its inferior lateral surface so deeply concave as to materially lessen it?- bulk. 

 This is also true of the next anterior centrum, and may be considered a 



