ON THE OSTEOLOGY OF NYCTOSAURUS. 159 
much longer than forearm; phalanges proportionally long. No fibula 
present; two tarsals only; fifth digit without phalanges. 
Ornithochetrine. Upper end of scapula thickened, articulating 
with a supraneural plate. Head with a prominent parieto-caccipital crest. 
Ornithocheirus. Jaws with teeth. 
Pteranodon (Ornithostoma). Jaws wholly edentulous. 
WVyctosaurine. Scapula flattened spatulate above, not PedTane 
with supraneural plate. Humeral crest constricted; humerus propor- 
tionally short, the digit long; no sagittal crest. 
Nyctosaurus, Ornithodesmus (?). 
In contradistinction to these characters I would define the P¢ero- 
dactylide as follows: I have never seen any specimen of this genus, and 
must, therefore, rely entirely upon the descriptions and figures. The 
characters hence are in a measure provisional. 
Pterodactylide. A distinct antorbital foramen present, sometimes 
partly confluent with the nares; occiput not produced, jaws always with 
teeth. No consolidation of the thoracic vertebrz or anchylosis of the 
sternal ribs, the posterior ribs less slender. More than ten vertebre in 
the dorsal region and less than six in the sacrum. Prepubes never co-ossi- 
fied in the middle, and without anterior prolongation. Scapula longer 
than the coracoid, more or less narrowed distally. Humerus and legs 
relatively large, the forearm and wing finger relatively small; all the meta- 
carpals articulating with the carpus. A fibula present. 
I am sure that all these characters are generalized ones, even as the 
genus is older than those placed in the first group. It seems to me 
especially that the shortening of the back, the consolidation of the early 
dorsal vertebrze, and the elongation of the sacrum, with the greater elonga- 
tion of the wing digit, are better evidences of relationships than is the 
presence of the peculiar scapular articulation. 
Certain conclusions as to the habits of the Orzzthochetrida, as I here 
define the family, seem inevitable from a better knowledge of their struc- 
ture. Some of these conclusions I have already presented in a former 
paper, and a further study only strengthens my belief in their justness. 
The neck was strong, with limited torsion, but with great power and 
effectiveness in the antero-posterior flexion, thus rendering the beak very 
effective in striking.* The marked posterior projection of the hind 
zygaphophyses of the last cervical vertebra, quite unlike those of any 
other vertebre in the colurmmn, indicates, not that the neck turned back- 
* Plieninger (op. cit.) misquotes me in saying that ‘‘ Williston glaubt, dass diese Art der 
Articulation die Bewegung des Halses in verticaler Richtung von vorne nach hinten eingeschrankt 
hat.” What I said was: ‘* Such a mode of articulation would seem to limit the motion to one ina 
vertical, antero-posterior plane, while greatly strengthening the joints.’’—Kans. Univ. Quart., vi, p. 39. 
