ORNITHOSAURIA. 229 



Pterodactylus and allied genera are small, short-tailed 

 Pterodactyls from the Lithographic Stone of Bavaria and 

 Wiirtemberg. In Pterodactylus itself the pubis much resembles 

 that of Dimorphodon, and the fifth digit of the pes is a mere 

 rudiment. 



Pteranodon (tig. 140). This genus comprises large and even gigantic 

 species of Cretaceous age. The skull is much elongated and laterally 

 compressed, and an enormous occipital crest is produced upwards and 

 backwards (fig. 140, c). The long axis of the quadrate (q) is inclined 

 downwards and forwards, and the orbit (6) is smaller than the confluent 

 antorbital and narial vacuities (a) ; there is a small supratemporal vacuity, 

 not shown in the accompanying figure. Sclerotic plates have been 

 observed. The jaws are entirely toothless, and the symphysis of the 



Fio. 140. 



Pteranodon longiceps ; skull from the left lateral aspect, one-twelfth nat. size. 

 Cretaceous ; Kansas, a, antorbital vacuity, including external narial 

 opening ; ft, orbit ; c, supraoccipital crest ; d, angle of mandible ; q, quad- 

 rate ; , symphysis of mandible ; the lateral temporal vacuity indicated, but 

 the supratemporal vacuity omitted in the figure. (After Marsh.) 



mandible is unusually elongated ; the texture of the bone suggests that 

 there was no horny beak. The occipital condyle is very small, hemi- 

 spherical, and not directed downwards so much as in the Jurassic genera. 

 The cervical vertebrae are elongated, and the tail is short. The scapula 

 and coracoid are fused together, and the support for the wing is further 

 strengthened by the articulation of the upper end of the scapula with the 

 neural spines of some fused anterior dorsal vertebrae. The radius and 

 ulna are separate and complete. The carpus comprises three bones, one 

 proximal, one distal, and one lateral ; and of these the proximal is the 

 largest, exhibiting distinct facettes for articulation with the radius and 

 ulna. In the manus the first digit is represented merely by a styliform 

 bone ; nos. n to iv are clawed, and exhibit the phalangeal formula 2, 3, 4, 

 but their metacarpals are incomplete, tapering to a point proximally, and 

 fixed only to the side of the enormously developed metacarpal of the fifth 

 or wing-digit. The latter has four much-elongated phalanges. The hind 



