246 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxvi. 



capituliim is borne on a heavy, rounded process, being well separated 

 from the weaker step-like tnberculum developed on the supero- 

 posterior border. Posteriorly, however, the capitular facets on the 

 vertebra^ gradually shift their position nearer to the tubercular facet, 

 and thus the distance between the capitulum and tnberculum of the 

 rib is gradually lessened. Fragmentarj^ ribs found articulated with 

 the dorsals of Cat. No. 4282, U.S.N.M., shows that the seventh 

 (counting from the last cervical) bears the heaviest rib of the series. 

 The posterior ribs are more slender, straighter, and shorter than those 

 anterior. 



The sacro-dorsal mentioned above must have borne a short, single- 

 headed rib, as indicated by the single capitular facet on the other 

 extremity of the weak transverse process (see fig. 89 and a, Plate 

 13), but there is no indication of ankylosis of the rib with the end 

 of the transverse, as Hulkc has found in this region of Hi/p-siJo- 

 phodon foxii. 



The sacral ribs will be found described in connection with the 

 sacrum on page 287, and the caudal i"ibs. or transverse ]:)rocesses, 

 with the caudal vertebra\ 



OSSIFIED TENDONS. 



In the matrix surrounding some of the vertebrae of No. 4282 there 

 are preserved a number of flattened, rod-like ossified tendons. In 

 this individual they were found as far forward as the eleventh 

 dorsal, and in the type of C. ncuiHs, on the eighth. These ossifications 

 are also present in the sacral region, and they undoubtedly occurred 

 along the spinous 2:)rocesses of the anterior caudals, although from 

 the condition of the available material this point can not be deter- 

 mined. The ends are much flattened and divided into a number of 

 ray-like points. They do not appear to have had any such develop- 

 ment as found in either Trachodon {Claosaurus) or Trk-eraiops. 

 These ossifications are shown at ot in fig. 39. 



In a paper on Hypsllophodon,'' Baron Nopcsa calls attention to 

 the presence of ossified tendons along the backbone of that animal, 

 and he also shows that these ossifications are present in all of the 

 British preclentate reptiles, with the exception of Scelidosaurus. In 

 the American members of this group they were first observed by 

 Marsh'' in Trachodon {Claosavrus) ^ and later in members of the 

 Ceratopsia by Hatcher.'* 



The arrangement of the tendons along the posterior dorsal vertebra? 

 jind over the sacrum is well represented in Plate 19, where they are 

 shown as found in the matrix. Their arrangement approximates the 

 conditions present in I g uanodon bernissartensis as figured by Dollo.^ 



« Phil. Trans. Roy. Soc. London, CLXXIII. 1882, p. 1047. 



''Geological Magazine. May. 1905, pp. 203-208. 



c Aiuer. Jonru. Sci., XLIV, Oct. 1892, p. 345. 



''Mon. U. S. Geol. Surv., XLIX, 1907, p. 51, fig. 48. 



" Bull. Bruxelles Mus. Roy. d'Hist. Xut. de Belgique, II, 1883, pi. v. 



