490 



GEOLOGY OF THE DENVEK BASIN. 



deep cavities in the sides and in the neural arch resembling those in the 

 corresponding vertebrae of Morosaiirus. The lnrabar vertebrae have their 

 articular faces more nearly plane, and the last lumbar is much expanded 

 transversely. 



Fio. 36.— Cervical vertebra of I atosaurus latieoUis Marsh ; back' 

 , ,11,. d aiapi jsisj/", lateral foramen; h, rib; y, parapophysi 



steenth rjatural size. 

 i /\ ^apophysis. 



Fig. 37.— Sacrum of Apatotaurus ajax Marsh; seen from below. One tenth natural size. 



o, first sacral vertebra b, sacral rib, or transverse procesB, of first vertebra; e, same process of second vertebra 

 os of tbird vertebra ■ t surfaces for union with ilia /,/, foramina between vertebra;! p, last sacral vertebra, 



The sacrum is characteristic of the genus, and quite unlike any hitherto 

 known. The type specimen on which the genus was established is well 

 shown in fig. 37. It is short and massive, and the three vertebrae which 



