On the Osteology of Nyctosaurus. 133 



they are widely separated from each other. A ridge extends downward 

 and posteriorly from the outer side of the zygapophysial process to the 

 outer side of the convex exapophysis or parapophysis. I find no foramen 

 inclosed between these processes, and can see no vestige of a cervical 

 rib, such as is described in certain European pterodactyls. The posterior 

 zygapophyses are concave and oblique, and above them, there is a more 

 or less prominent process, a sort of " metapophysis." They do not extend 

 as far back as the ball, leaving a wide space between and back of them in 

 which the floor of the neural canal is visible. The laminae are broad, thin, 

 and roof-like, meeting in the middle and forming a very thin, neural 

 spine. The length of the base of this spine varies not a little in the 

 different vertebrae, from twelve to sixteen millimeters. In only one 

 vertebra is there a long spine, the one figured in PI. XLI V, Fig. 1 7, which I 

 take to be the seventh cervical. In the others, the free, thin border slopes 

 slightly upward and forward, forming a rounded spine but a few milli- 

 meters in height. 



Eighth cervical vertebra. Pl.XLIII, Fig. 8. The eighth vertebra, which, 

 as already explained, is a real cervical and not a dorsal, was lying close to 

 the first notarial vertebra, and near the presternal process of the sacrum. 

 It has been so much compressed that all of its characters cannot be made 

 out with clearness. A figure of it is given as it lay in the matrix. It 

 differs greatly from the vertebra preceding it in the shortness of its 

 centrum, the character of its spine, and in the presence of diapophy- 

 ses. The ball is transversely widened, and has, at each extremity, 

 a large, concave, articular exapophysis. The post-zygapophyses are 

 situated much posteriorly to the ball, differing therein remarkably from 

 those of the preceding vertebrae. The spine above the zygapophyses is 

 very short and thick; seen from behind, it is concave, and ends obtusely 

 nearly over the zygapophyses. On each lateral expansion, near the upper 

 extremity, there is an oval, rounded, smooth surface, forming a sort of 

 process corresponding to the " metapophyses " of the earlier vertebrae. 

 The front border of the spine is concave in outline, and is rounded. 

 There is a rather slender and moderately long diapophysis, springing 

 high up on the arch. In the specimen it has been compressed against 

 the vertebra, but seems to end in an articular process. On the under 

 side of the vertebra, near the mutilated diapophysis, there is a fragment 

 of a rib, more slender than those of the notarium, which probably belongs 

 with this vertebra. In the much confused anterior end of this vertebra, 

 there is a small process on each side, evidently the exapophysis, which may 

 also have served for the articulation of the head of the rib; if so, how- 

 ever, the head must have been small. In the specimens of the Pteranodon 

 vertebrae already described, this parapophysis seems either rudimentary or 



