132 FIELD CoLUMBIAN MusrEuM—GEOLOGY, VOL. II. 
lying upon their ventral surface, that is, compressed dorso-ventrally, and 
two were more or less crushed laterally or obliquely. There is less 
difference in the lengths of the five following the axis than is the case in 
Preranodon,; { am therefore somewhat in doubt as to the precise position 
of some of them. Those that are depressed have the under surface 
irregularly plane or concave, with the lateral margins rounded and 
concave, formed by the ridge which reaches from the anterior zygapo- 
physis and exapophysis on each side to the corresponding posterior 
exapophysis. At the front margin there is an oval fossa, or depression, 
on each side, separated by a convex surface; this convexity seems often 
to be produced into a distinct hypapophysis in the European pterodactyls. 
In a previous paper I stated that the exapophyses are non-articular in this 
genus. ‘This statement, after a more careful examination of the speci- 
mens removed from the matrix, I know to be erroneous, at least so far 
as the processes of the posterior vertebrz are concerned. Owen has 
identified these processes with the parapophyses, and Plieninger prefers 
to adopt this name for them. As will be seen by an inspection of Fig. 
7, Pl. XLIII, the true parapophysis—that is the process for the articulation 
of the head of the rib, for which the term was originally introduced by 
Owen, and in which sense it is now used—is always situated at the anterior 
end of the vertebra, close to the rim of the cup. This process bears on 
its anterior face, close to the rim of the cup, a convex, articular surface 
for union with the corresponding concave surface of the ‘ posterior 
parapophyses” of the preceding vertebra. One might with as 
much propriety call these posterior prominent articular processes the 
diapophyses, or posterior inferior zygapophyses, as “posterior para- 
pophyses.”’ ‘There is no such thing as a posterior parapophysis, nor can 
there be. Nor could these posterior ‘‘ parapophyses”’ ever have arisen 
as processes for rib articulation. They are very characteristic of the 
pterodactyl vertebrz, taking the place of the lateral or double articula- 
tion of the cryptodire testudinate cervical vertebrae. I have given these 
articulations a distinctive name of exapophyses in order to save much 
circumlocution in their description; in any event they should not be 
called “‘parapophyses,” since they have nothing to do with these processes, 
either morphologically or functionally. 
The cup and ball are widened transversely; in the depressed specimens 
very much so, and this is not due to their crushing, since those lying upon 
their sides, though mutilated, still preserve evidence of a lateral elonga- 
tion of the articular surface. ‘The convexity of the ball is marked dorso- 
ventrally, more so near the neural side. The posterior border between the 
exapophyses is thin and concave, nearly concealing the ball, when seen 
from below. The anterior zygapophyses project much in front of the cup; 
