ON THE OSTEOLOGY OF NYCTOSAURUS. 129 
surface is oval, the plane of each nearly at right angles with that of its mate. 
The spine is broad and transverse; from the front it presents a median 
ridge. On the under side the centrum is flat, the flatness reaching nearly 
to the extremity of the parapophysis; the width is considerably greater 
than the length. The posterior surface of the centrum in this specimen 
is distinctly roughened for sutural union with the following centrum; the 
posterior zygapophyses also unite with the succeeding ones suturally. 
This vertebra is very clearly the first of the notarium, as Seeley has hap- 
pily called the united dorsal vertebre. ‘‘ Two other vertebrz found close 
by the one described, and possibly one or the other contiguous with it, 
differ remarkably in having no or a rudamentary parapophysial process, 
and in having the diapophysis much shorter.”” “In /Preranodon there are 
at least four vertebrz with dia- and parapophyses.” ‘In two other 
centra there is a long, recurved, parapophysial process, as though formed 
by an anchylosed rib, on each side; they are probably lumbar vertebre.”’ 
It is very clear, however, that these last two vertebre are not lumbars, but 
separated elements of the notarium. Of the two other vertebrz men- 
tioned, one is probably the eighth cervical, described below, while the 
other may be the fourth dorsal. 
In Pteranodon, 1 thought there might be two vertebre intervening 
between the elongated cervicals and the notarium. ‘‘ The centrum is‘short 
and broad, so different from the preceding one that it is possible there 
may be an. intervening one lost. The ball is more than four times as 
broad as high, concave on the upper margin, convex below. The post- 
exapophyses are large, and confluent with the articular faces of the ball, 
but are concave. The convex pre-exapophyses, at the outer side of the 
cup are at the base of the lower root (that is the parapophysis) of the 
elongated transverse process.”* This vertebra corresponds with the 
eighth post-cranial vertebra of the present specimen, but an “imperfect 
vertebra, evidently following the one described, has the centrum very simi- 
lar, save that the spine appears to be less stout.’ I cannot at the present 
time examine this specimen, but it is probable that it is the first separated 
vertebra of the notarium. 
From the foregoing, then, it seems assured that there is a free, short 
vertebra in front of the notarium, in both Péeranodon and Vyctosaurus, 
bearing a free, small rib, which does not unite with the sternum. This ver- 
tebra is the eighth cervical, and is probably present in all pterodactyls. It 
is strange that authors, in the description of the neck bones of the ptero- 
dactyls should have so often spoken of the united atlas and axis as one 
vertebra, thus reckoning seven instead of eight vertebra in this part of the 
* Williston, Kansas University Quarterly, vol. vi, p. 4o. 
