OSTEOLOGY OF THE AHMOEED DINOSAXJEIA. 

 Measurements of caudal vertebrae of Stegosaurus — Continued. 



61 



No. 

 of 

 ver- 

 te- 

 brae 

 in se- 

 ries. 



30. 

 31. 

 32. 

 33. 

 34. 

 35. 

 36. 

 37. 

 38. 

 39. 

 40. 

 41. 

 42. 

 43. 

 44. 

 45. 

 46. 

 47. 



Greatest length of centra. 



Greatest transverse diameter 

 posterior end of centra. 



Greatest height of vertebrae, 

 over all. 



No. 

 4288. 



No. 

 4714. 



48 

 45 

 44 

 41 

 40 

 38 

 37 

 36 

 33 

 33 

 29 

 29 

 23 

 18 

 18 

 18 

 18 



No. 

 4934. 



No. 

 6099. 



■mm. 

 53 

 48 

 46 

 45 

 45 

 41 

 40 

 36 

 36 

 36 

 35 

 30 

 27 

 25 

 18 

 9-1- 



No. 

 6135. 



S3 

 61 

 48 

 48 

 45 

 40 

 38 

 36 

 35 

 32 

 30 

 26 

 23 

 22 

 19 

 18 

 16 

 8-1- 



No. 

 6531. 



mm. 

 48 

 48 

 47 

 44 

 42 

 40 

 37 

 35 

 33 

 33 

 30 

 29 

 26 

 24 

 21 

 21 



No, 

 6629. 



43 

 42 

 41 

 39 

 38 

 36 

 34 

 34 

 31 

 30 

 27 

 24 

 23 

 22 

 19 

 19 

 17 

 94- 



No. 

 4288. 



mm. 



No. 

 4714. 



mm. 

 46 

 43 

 43 

 38 

 39 



No. 

 4934. 



mm. 



No. 

 6099. 



No. 

 6133. 



mm. 

 46 

 48 



47 



No. 

 6531. 



mm. 

 47 



No. 

 6629. 



mm. 

 44 



No. 

 4288. 



No. 

 4714. 



No. 

 4934. 



mm. 



No. 

 6099. 



mm. 



No. 

 6135. 



103 

 103 



No. 

 6531. 



mm. 



No., 

 6629. 



mm. 



42 

 42 

 39 

 35 

 33 

 32 

 29 

 29 

 26 

 27 

 26 

 23 

 20 

 18 

 18 

 16 

 14 

 14 





50 

 43 





94 

 85 

 75 

 67 

 62 

 60 

 55 

 4S 









91 



44 

 42 

 41 

 38 

 37 

 35 

 33 

 29 

 27 

 26 

 25 

 24 

 22 

 19 











42 

 40 

 39 

















37 



39 











73 

















35 



37 

 35 



28 

 25 

 23 

 28 

 27 

 21 

 16 

 12 

 11 



















34 

 32 

 31 

 28 

 26 









49 













30 

 31 

 30 

 25 

 23 

 19 

 16 



































40 

 36 

 29 

 24 

 21 

 18 

 18 







32 

 28 

















33 

 30 

 25 

 25 





















21 

 19 

 18 

 12 



















19 

 13 

 11 



















































































Chevrons. 



The chevrons of Stegosaurus are noteworthy on account of the great transverse 

 width of their proximal ends, when compared to their short length. They have 

 the usual Y-shape, with expanded articular surfaces. In some individuals (fig. 29) 

 the chevrons of the anterior portion of the tail have these ends united medially by 

 a bridge of b.one, thus entirely inclosing the hsemal canal. This condition, how- 

 ever, is variable, for in S. stenops, No. 4934, two chevrons, apparently the first and 

 second of the series, have distinct articular ends. In other specimens one chevron 

 will be bridged and the next will show the articular surfaces separate (fig. 30). 

 The above conditions prevail only among the chevrons of the anterior half of the 

 tail, for aU specimens agree in having those of the distal portion divided proximally. 



The chevrons of the anterior half of the tail, when compared with those of 

 Camptosaurus, Iguanodon, and Trachodon, are short and stout, with especially 

 large haemal openings. The free or distal end is expanded antero-posteriorly, and 

 excepting a few of the most anterior ones, has a decided backward sweep, which 

 becomes more and more pronounced as the distal end of the tail is approached. 

 The successive changes that take place are well shown in figure 29. 



The chevrons articidate intervertebraUy and, beginning with the third caudal, 

 continue, as shown in specimen No. 4714, to the next to the last vertebrae of the 

 series (pi. 16). 



Marsh has indicated, in his restoration of the skeleton, that the first chevron 

 is between the third and fourth caudals. In this he is probably correct, although 

 the evidence offered by specimens in the National Museum is not altogether con- 

 clusive. As mentioned previously, there are no distinct chevron facets on the 



