238 



REPTILIA 



CLASS III 



acetabular portion much extended, and the ischium has an obturator process. 

 Supposed sternal ossifications sometimes occur. 



Gamptosaurus, Marsh (Camptonotus, Marsh). Attaining a total length of 

 about 10 in. Cervical ribs short; dorsal vertebrae amphiplatyan ; sacrals 

 not anchylosed. Pubis robust, post-pubis of equal length with the long and 

 slender ischium. Pendent inner fourth trochanter of femur very marked. 

 Proximal tarsals separated. Upper Jura ; Wyoming and Colorado. Kim- 

 meridgian and Wealden ; England. 



Laosaurus, Dryosaurus, Nanosaurus, Marsh. Upper Jura; Wyoming and 

 Colorado. 



Hypsilophodon, Huxley. Premaxillae each with five small deeply-socketed 

 lateral teeth, edentulous and beak-like in front; nasals elongated. Vertebrae 

 amphiplatyan. Sternum partly ossified. Post-pubis of equal length with the 



Pmx-fr. 



Fig. 340. 



Iguanodon bernissartensis, Boul. Wealden; Bernissart, Belgium. Skull, Vs- -1, Orbit ; art, Articular ; d, 

 I >entary ; fir, Frontal ; ju, Jugal ; la, Lachrymal ; mx, Maxilla ; N, External nostril ; na, Nasal ; pa, Parietal ; 

 I 'redentary ; <pmx, Premaxilla ; ptf, Postf rental ; qu, Quadrate; quj, Quadrato -jugal ; S, Supra temporal 

 \ acuity ; sq, Squamosal: x, y, Supraorbitals (after Dollo). 



ischium ; proximal tarsals separated ; manus and pes each with four clawed 

 digits. Known by several complete skeletons 1*5 m. long from the Wealden 

 of the Isle of Wight. 



Iguanodon, Mantell (Figs. 340-342). Skull laterally compressed, with 

 Large, nearly terminal nostrils, and small antorbital vacuity. Orbits deeper 

 I lian wide, smaller than the irregularly triangular or elongated lateral temporal 

 vacuity. Supratemporal vacuities of moderate size, separated by the narrow 

 parietals, which meet in a sharp median crest. Two small supraorbital bones 

 above the eye, but no sclerotic ring. Frontals flattened and apparently fused; 

 nasals elongated. Mandibular suspensorium nearly vertical ; articular portion 

 of the quadrate at the base of an unusually deep pedicle. Jugal crescentic, 

 bounding the orbit inferiorly ; quadrato-jugal rather large; lachrymal small. 

 Premaxillae toothless, but with sharpened margin. Maxillae and dentary 

 with numerous closely-set grinding teeth arranged in a single row ; the teeth 

 when unworn are spatulate, loosely socketed, and with serrated margins ; 

 mccessional teeth well formed below those of the functional row. Mandibular 



