^ OKNITHOSAURIA. 



condylar groove ; proximal row of tarsus consisting of astragalus 

 and calcaneum. Abdominal ribs generally present. In the limbs 

 the number of phalangeals is liable to variation, although approxi- 

 mating, more or less, to the arrangement obtaining in the Squamata 

 (infra). There may be a lateral vacuity in the mandible. 



Order OENITHOSAURIA. 



Pectoral limb adapted to support a patagium ; body probably 

 naked. Vertebrae procoelous, without persistent neuro-central 

 suture ; cervicals longer than dorsals ; precaudals not numerous ; 

 from three to six in sacrum 1 ; cervical ribs, at least in RJiam-pho- 

 rliynch.us, crocodilian 2 . Skull large, more or less bird-like in 

 contour, with the bones anchylosed in the adult ; jaws elongated, the 

 greater portion of upper one formed by premaxilla ; mandibular sym- 

 physis anchylosed ; occipital condyle situated on base of cranium. 

 Orbits large, usually with sclerotic ossifications 3 ; narial aperture 

 approximated to orbit, but separated by preorbital vacuity, with 

 which it may be confluent. Teeth simple and pointed. Scapula 

 and coracoid long and slender, latter without fontanelle ; no clavicle ; 

 sternum broad, and keeled superiorly. Carpus with a proximal and 

 distal bone ; four functional digits in manus ; phalangeals of ulnar 

 digit 4 of manus much elongated, and terminal one not clawed. 

 Pelvis weak ; ilium generally extended on both sides of acetabulum ; 

 pubis directed forwards ; ischium short and wide ; pelvic limb 

 short ; fibula, and sometimes astragalus, united with tibia. Bones 

 hollow, and frequently with pneumatic foramina. Habits volant. 

 The brain seems to have been bird-like. 



1 Seeley (' Ornithosauna, pp. 110, 111) states that there are but two anchy- 

 losed vertebrae in the sacrum of Scaphognathus {Pachyrhamphus), and none in 

 that of Dimorphodon. 



2 See Baur, ' Amer. Nat.' 1886, p. 980. 



3 Perhaps wanting in Pteranodontia. 



4 Regarded by Owen, Marsh, and Zittel (' Palaeontographica,' vol. xxix. p. 54) 

 as the fifth of the typical series; the styliforin ossification on the radial side of 

 the carpus (fig. 3) representing the pollex. 



