MYCTEEOSTJCHUS NASUTUS. 



139 



the twelfth vertebra, or the first in which the caudal ribs are wanting, the upper 

 portion of the spine is narrowed by a broad notch on its anterior edge (PL VIII. 

 fig. 5), dividing it into the main spine behind and a narrow pointed process in front, 

 projecting nearly vertically upwards. Still farther back a posterior notch appears : 

 at first this merely forms a kind of bay in the posterior border of the spine, but 

 becoming larger in the more posterior vertebrae, it separates off from the main spine 

 a posterior prominence similar to that in front (PI. VIII. fig. 6). These anterior and 

 posterior processes of the neural spine are continued nearly to the end of the tail 

 (PI. VIII. figs. 7-8), and in the posterior vertebrae have a deceptive resemblance to 

 zygapophysial processes, though an examination of their mode of origin shows that 

 they are not so, but merely portions of the neural spine. In the posterior vertebra? 



Sacral vertebrae of Mycterosuclius nasutvs, from below. (K. 3892, | nat. size.) 



ax., anterior end of centra ; U.S., surface for ilium ; p.c, posterior surface of centrum ; 



s.r., sacral ribs. 



the main part of the neural spine shifts further and further back on the arch, and at 

 the same time becomes smaller. 



The shoulder-girdle (text-fig. 54, C), in correlation with the relatively large size of the 

 fore limb, is strongly developed, both the coracoid and scapula being much expanded 

 at their extremities. 



The humerus (text-fig. 54, A, I>) is large compared with that of Steneosaurus and 

 differs from it in several other respects. Thus the upper end seems to be less 

 bent backwards, and consequently its articular surface is more nearly terminal. At 

 the distal end both condyles are well developed, though the radial one (c.c.) is the 



