Nodosaurus textilis Marsh. 115 



Hind Limh. 



The limb-bones of the type specmien of Nodosaurus 

 differ decidedly from those of Stegosaurus or Hophto- 

 saurus in the smoothly rounded character of the articular 

 ends, Xvhich in the latter genera are rugose, indicatmg 

 articular cartilages of considerable thickness. The carti- 

 lage in Nodosaurus was doubtless relatively considerably 

 reduced. On the other hand, the surface grain is more 

 distinct in Nodosaurus, giving a fibrous character to the 

 bone which seems to be unique. These features, together 

 with the extreme ankylosis of tibia and astragalus (see 

 below), are interpreted as indications of the advanced 

 age of the individual, in which the articular cartilages 

 would become more perfectly ossified and the bony tissue 

 of the limb bones might in a sense invade the tendinous 

 muscular attachments as well. (See pi. IV, figs. 4, 5.) 



Femur (pi. lY, fig. 4; text fig. 5).— The left femur is 

 complete as to length and well preserved, although 

 portions are missing, notably in the region of the several 

 trochanters, the extent of which can not, therefore, be 

 ascertained. The bone is less straight than in Stego- 

 saurus, and in its degree of curvature resembles more 

 nearly that of Hoplitosaurus (Gilmore 1914, fig. 69), 

 especiallv when comparison is made with the actual bone 

 (U. S. N. M. No. 4752). In Mr. Gilmore 's figure {fig. 

 69, 3) the low^er curve of the shaft has been exaggerated 

 to correct for crushing, giving a decided S-shaped outline 

 to the bone when viewed from the side. Thus the knee 

 of Nodosaurus must have been habitually partially flexed, 

 giving a very different appearance to the limb from that 

 of the mounted Stegosaurus ungulatus at Yale (Lull 1910, 

 pi. II and fig. 2). The surface of the shaft in the Nodo- 

 saurus femur also agrees with Hoplitosaurus rather 

 than Stegosaurus in that th-e limitations of the muscle 

 areas are clearly defined by well developed ridges, 

 whereas in Stegosaurus the surface is relatively smooth. 

 The great trochanter is missing, but the preserved 

 outline of the summit of the bone seems to indicate that 

 it was more prominent than in either Hoplitosaurus or 

 Stegosaurus, as figure 5 shows. 



Wliile the fourth trochanter is missing from the bone, 

 there is no reason to suppose that it was more than a 

 mere roughened area for the insertion of the caudo- 

 femoral muscle. This is in keeping with the strictly 

 quadrupedal gait of the animal. The anterior aspect 



