Nodosaurus textilis Marsh. 101 



of the left side and portions of the vertebrae preceding 

 and following. They seem to pertain to, or to be 

 somewhat posterior to, the mid-dorsal region. The mass 

 also contains the antero-posterior calcified tendons lying 

 on either side of the spinous process, and the overlying 

 armor of the left side. The vertebrae themselves resem- 

 ble those of Stegosaiirus somewhat, but diifer in that they 

 do not show the extreme exaggeration of the elevation of 

 the neural arch. They are in this respect more nearly 

 of the proportions of Polacanthus and Struthiosaurus, 

 in that the diapophyses originate slightly below the 

 zygapophyses, although distally they rise above them. 

 In so far as the centra are preserved, either in bone or 

 by matrix impression, they are quite stegosaur-like. 

 Laterally the centra show a distinct concavity as in 

 Stegosaurus, but there is nothing comparable to a 

 pleurocoele. The neural arch is robust, as are the 



Fig. 1. — Dermal [subdermal] ossicles of Nodosaurus textilis. After Marsh. 

 Natural size. 



prezygapophyses, to which a portion of the postzygapo- 

 physes of the preceding vertebra, together with the 

 spinous process, are so firmly united, in part by matrix, 

 that the line of demarcation is nearly invisible. The 

 diapophyses are curved on their external margin and are 

 firmly ankylosed with the superior surface of the capit- 

 ulum of the rib, as in Ankylosaurus; the two elements 

 are clearly separated, however, by a deep groove. "So 

 far as one can see, the low tuberculum of the rib seems 

 to be free from the diapophysis, but the space between 

 is filled with an apparent matrix which is with great 

 difficulty, and not always with certainty, distinguishable 

 from bone. The neural canal is oval in section, with 

 the apex uppermost, and is of considerable size. 



The ankylosed left rib abuts against the neural arch, 

 the facet being elliptical and elongated vertically. The 

 rib has a sigmoid curve, being ventrally convex to the 

 level of the tuberculum and thence concave. Beyond 

 the tuberculum it is distinctly T-shaped in cross-section, 



