WILLISTON: THE SACRUM OF MOROSAURUS. 175 
the accompanying figures. Its flat anterior surface and the shape 
of the transverse processes are very different. 
Fig.2. Sacrum of Morosaurus grandis, from the side. 
On either side of the broad plate, at the extreme ends, there is 
a thickening, tipped with cartilage. The same protuberance is 
found on the much smaller plate of the second vertebra. It is 
apparently wanting in the succeeding vertebrae, whose plates are 
much reduced. The middle three spines of this specimen, as in 
the other genera, are firmly coossified. The first vertebra is closely 
united as far as the bottom of the spine, but the spine itself is free. 
The generic identity of the present specimen is assured by the 
finding of the complete ischia in immediate conjunction with the 
sacrum. Aside from a number of dorsal, cervical and caudal 
vertebrae, all clearly belonging with the same individual, there were 
no other bones in the ‘‘quarry” whence the specimen came. 
