ON THE OSTEOLOGY OF NYCTOSAURUS. Tis 
slightly removed. The length of the series is about fifty millimeters, 
showing that five vertebre are associated in it, and that the protruding 
one is the fifth. Whether the fourth and fifth are both suturally united 
in the notarium cannot be said, but in all probability the fifth at least is 
free, since its convexity shows it to be of the nature of the following ones, 
and because one of the small posterior ribs seems to have been articulated 
with it. The sixth, seventh, eighth, and ninth vertebre are nearly in 
relation with each other, behind the sternum, lying upon their dorsal 
side, but are pushed somewhat to the left. They are cylindrical in cross- 
section, with smooth, evenly concave sides and inferior border, with a 
deep cup and a prominent ball. They are a little longer than broad, of 
nearly equal length, though a little more slender posteriorly. The ante- 
rior zygapophyses extend in front of the cup. The elongated and slender 
diapophyses arise high up on the arch from near the anterior part of the 
vertebra, and are directed horizontally outward. These vertebre are quite 
similar to those of Pteranodon, and are doubtless quite like that figured 
by Seeley in his Dragons of the Air, p. 86, Fig. 26. The last dorsal (or 
first sacral) (Pl. XLI, Fig. 1, dv), the tenth back of the neck, is flat on its 
inferior surface, and its transverse process I think arises from the centrum 
as in Preranodon. It is firmly united with the sacrum by suture in both 
genera, and is quite as properly counted with the sacrum as with the 
dorsal or lumbar vertebre. It is probable that its transverse process 
unites with, or reaches to, the anterior projection of the ilium, as seems 
also to be the case in P¢eranodon. 
The position in which the skeleton is lying indicates that the right 
coraco-scapula and the pelvis are in the positions in which they were as 
regards each other while yet held together by the ligaments. The right 
arm, falling across the abdomen, has caused a slight dislocation of the 
dorsal vertebrze, the notarium held by the ribs has been turned somewhat 
obliquely, and the sternum has settled down alittle to the left. The 
ends of the scapulze, however, are nearly in the relative position to each 
other which they must have held during life, and the axis of the sacrum 
is in line nearly with the presternum. 
Now, by bringing all the vertebre back into a straight line, the ten 
vertebrz fill the entire space between the neck and the true sacrum, 
proving almost incontestably that there were neither more nor less than 
ten, a number found in no other reptiles except the turtles and Pareza- 
saurus; indeed, if we call the last a sacral, then there are fewer presacral 
vertebre in /Vycfosaurus than in any other known reptile. 
The sacrum proper, as described below, is composed of six vertebra, 
the lines of sutural union of which are clearly visible in the specimen. 
Four caudal vertebre are preserved, lying close to the proximal end 
