maesh.J CAMPTOSAURIDiE. 197 



The skull, brain, and teeth of C. medius are shown on PI. MIL 

 The peculiar peg-and-noteh articulation in the sacral vertebras of this 

 genus, already described elsewhere, is indicated on PI. LIV, figs. 3 and 

 4, and a summary of the principal characters of the genus, and of the 

 nearest allied genera, will be found on p. 201. 



RESTORATION OF CAMPTOSATTRUS. 

 Plate LVI. 



The restoration here given is based upon the type specimen of Camp- 

 tosaurus dispar, one of the most characteristic forms of the great group 

 Ornithopoda, or bird-footed dinosaurs. The reptile is represented on 

 PI. LVI, one-thirtieth natural size. The position chosen was deter- 

 mined after a careful study not only of the type specimen, but of sev- 

 eral others in excellent preservation, belonging to the same species or 

 to others nearly allied. It is therefore believed to be a position fre- 

 quently assumed by the animal during life, and thus, in some measure, 

 characteristic of the genus Camptosaurus. The type specimen of the 

 present species, when alive, was about 20 feet in length, and 10 feet 

 high in the position here represented. 



The genus Camptosaurus is a near ally of Iguanodon of Europe, and 

 may be considered its American representative. Camptosaurus, how- 

 ever, is a more generalized type, as might be expected from its lower 

 geological horizon. It resembles more nearly some of the Jurassic forms 

 in England generally referred to Iguanodon, but as these are known 

 only from fragmentary specimens their generic relations with Campto- 

 saurus can not now be determined with certainty. 



In comparing Camptosaurus, as here restored, with a very perfect 

 skeleton of Iguanodon from Belgium, as described and figured, various 

 points of difference as well as of resemblance may be noticed. The skull 

 of Camptosaurus had a sharp, pointed beak, evidently encased during 

 life in a horny sheath. This was met below by a similar covering, which 

 inclosed the predentary bone. The entire front of the upper and lower 

 jaws was thus edentulous, as in Iguanodon, but of different shape. The 

 teeth of the two genera are of similar form, and were implanted in like 

 manner in the maxillary and dentary bones. In Camptosaurus there 

 is over each orbit a single supraorbital bone, curving outward and 

 backward, with a free extremity, as in the existing monitor, a feature 

 not before observed in any other dinosaur except Laosaurus, an allied 

 genus, also from the Jurassic of America. Other portions of the skull 

 of Camptosaurus, as well as the hyoid bones, appear to agree in general 

 with those of Iguanodon. 



The vertebrae of Camptosaurus are similar in many respects to those 

 of Iguanodon, but differ in some important features. ,In the posterior 

 dorsal region the transverse processes support both the head and tuber- 

 cle of the rib, the head resting on a step, as in existing crocodiles. 

 The five sacral vertebra;, moreover, are not coossified even in adult 



