ORDER IX PTEROSAURIA 247 



axis extending nearly at right angles with the neck. Investing hones of lemforal 

 region contracting into an upper and a lower arcade ; sutures becoming obliterated in 

 the adult. Quadrate large, firmly fixed ; orbit very large, and usually with sclerotic 

 ring ; antorbital vacuity large, sometimes confluent with external nares. Teeth, when 

 present, slender, conical, thecodont, and confined to margin of the jaws. Mandibular 

 rami fused at the symphysis. Presacral vertebrae procoelous, ccmdals amphicoelous ; 

 sacralsfour to seven in number, usually fused. Cervical and anterior dorsal ribs double- 

 headed. Sternum large, clavicular elements wanting, scapula and coracoid long and 

 slender. Fifth digit of manus enormously elongated and reflexed to support the wing 

 membrane. Pubis excluded from the closed acetabulum. Both rows of tarsals ossified, 

 the astragalus sometimes fused with the tibia. Two to four digits of the pes bear claws, 

 the fifth digit sometimes vestigicd. Abdomincd ribs present ; no dermal armour. 



The Pterosauria or Ornithosauria, as they are also called, constitute an 

 extraordinary group of extinct reptiles, ranging from the Lias to the Upper 

 Cretaceous. They are remarkably bird -like in general appearance, and 

 their whole organisation is modified for the accomplishment of flight through 

 the air. In the larger number, however, the power of flight was more limited 

 than in birds, and may have been in many forms feebler than in bats. The 

 skeleton was more or less pneumatic, like that of birds, and the general 

 avian appearance was accentuated by the articulation of the head at right 

 angles to the cervical axis. Some of these bizarre creatures were no larger 

 than sparrows, but others, with whose extinction the history of the race 

 terminates, were of gigantic size, the spread of their cutaneous expansion 

 being nearly 6 m. from tip to tip. 



The vertebral column comprises seven true cervicals, twelve to sixteen 

 dorsals, four to seven sacrals, and ten to forty caudals. The presacral vertebrae 

 are procoelous, and the caudal amphicoelous. The neural arches are usually 

 fused with their centra, and the sides of the latter are more or less extensively 

 hollowed. Cervical ribs, when present, are very much shorter than the dorsal 

 ribs. The latter are double-headed anteriorly, but become single-headed and 

 more slender toward the sacral region. Transverse processes are very strongly 

 developed in the anterior sacral vertebrae. There is a triple series of small 

 V-shaped abdominal ribs along the ventral wall of the body cavity. 



The skull (Fig. 352) is remarkably bird-like in form, and its constituent 

 elements usually become anchylosed at an early age. The orbits are very 

 large, laterally placed, and surrounded by a sclerotic ring of small plates. An 



p. 63), 1831. — Huxlei/, T. H., On Rhampliorhynchiis Bucklandi (Quar. Joiirii. Geol. Soc. vol. XV. 

 p. 658), 1860. — Marsh, 0. C, Various articles in Amer. Journ. Sci. [3], 1871-84 (vols. I.- p. 472 ; 

 III. p. 241 ; XL p. 507 ; XII. p. 479 ; XVI. p. 233 ; XXI. p. 342 ; XXIII. p. 251 ; XXVII. p. 

 423,' etc.). — Meyer, H.von, Reptilien aus dem lithographischen Schiefer( Fauna cler Vorvvelt, pt. IV.), 

 1860. — Xeivton, E. T., On the skull, brain, and auditory organ of Scaphognatlius purdoni (Phil. 

 Trans, vol. CLXXIX. B, p. 5u3), 1888.— Notes on Pterodactyles (Proc. Geol. Assoc, vol. X.), 1888. 

 — Owen, R., Reptilia of the Liassic Formations (Palaeontogr. Soc. pt. II.), 1863. — Plieninger, F., 

 Campylognathus Zitteli ( Palaeontogr. vol. XLL), 1894. — Beitriige zur Kenntniss der Flugsaurier 

 (ibid. vol. XLVIIL), 1901. — Qv.enstedt, F. A., Ueber Pterodactylus suevicus. Tiibiugen, 1855. 

 — Seeley, H. G., The Ornithosauria. Cambridge, 1870. — On the organisation of the Ornithosauria 

 (Journ. Linn. Soc. vol. XIII. ), 1884. — The Ornithosanriau pelvis (Ann. Mag. Nat. Hist. [6], vol. 

 VII. p. 237), 1891. — On the shoulder-girdle in Cretaceous Ornithosauria [ibid. p. 438). — Dragons' 

 of the Air, London, 1901. — Wagner, A., Contributions on Upper Jurassic Pterosaurs in Abhaudl. 

 Bayer. Akad. Wissensch. math.-phys. Classe, vols. II. p. 163; VI. pp. 129, 690; VIII. p. 439 

 (1837-58). — ■Williston, S. W., On the skull of Ornithostoma (Kansas LTniv. Quar. vol. IV. p. 195), 

 1896. — Pi,estoration of Ornithostoma (Pteranodon), [ibid. vol. VI. p. 35), 1897. — Zittel, K. A., 

 Ueber Flugsaurier aus dem lithographischen Schiefer (Palaeontogr. vol. XXIX. p. 49), 1882. 



