724 STUDIES FOR STUDENTS 
synonymous with Ornzthostoma. Head much elongate; the jaws 
slender, pointed and wholly wanting teeth; external nares and 
antorbital vacuities united; supratemporal fossa of large size; 
occipital crest elongated; the anterior dorsal vertebre united 
and bearing a supraneural plate for articulation with the scapule ; 
tail short and small; four functional toes on the hind foot. 
Speaking of the general appearance of the animal, Dr. Wil- 
liston says: “Altogether the skeleton of Ornithostoma presents 
some remarkable characters. I believe there is no other reptile in 
which the prosthenic features are carried to as high a degree as 
in this. The disproportion between the fore and hind extremi- 
ties is almost ludicrous. The pelvis is exceedingly small, the 
legs not only small but weak in all respects. That the animal 
could have stood on its feet free on the ground I do not believe 
possible. The neck vertebre are relatively stout, but the neck 
was not remarkably elongated, to carry such a head as the ani- 
mal possessed, Furthermore, the remarkable mode of articula- 
tion of the neck and the anterior dorsal vertebrae seem to indi- 
cate a restricted range of torsion, though tolerably wide sagittal 
flexion. The occurrence of the remains of the large species in 
strata evidently formed remote from the shore lines, as shown by 
the absence of other animals, turtles, etc., indicates great powers 
of flight. Furthermore, it is rare that a single bone of a Péero- 
dactyl is found unassociated with others, and almost invariably 
the wing bones are found more or less in connection, indicating 
either tough and horny tendons or a rapid sinking in the water, 
which might happen from the filling of the hollow bones with 
water through their pneumatic openings. 
‘Notwithstanding the enormous expanse of the wings, I do 
not think these animals could have weighed much when alive. I 
doubt very much if one of the largest species reached twenty 
pounds.” 
Nyctodactylus was a form from the Cretaceous of Kansas ( Nio- 
brara) that differed from the previous genus principally in the 
size, the wings measuring less than ten feet when expanded. 
The jaws were almost certainly edentulous. 
