62 



BULLETIN" 89, UNITED STATES NATIONAL MUSEUM. 



anterior caudals, and in specimens Nos. 4714, 4934, and 6531, the sixth or seventh 

 centrum from the sacrum is the first to show facets. Two disarticulated chevrons 

 are retained in the rock just below caudals three and four in specimen No. 4934 

 (pi. 2), and as mentioned above evidently represent the first and second. With 

 specimen No. 4714, chevrons were also found in place in the matrix forward of the 



Fig. 29.— Cheyeoxs of Stegosauecs sp. Cat no. 6531, TJ.S.N.M. J nat size. A, Side view of chevrons fbomantebioe, 



MEDIAE, AND POSTEEIOE PARTS OF THE TAIL. B, SAME, VIEWED POSTEEIOELT. 



sixth of the series, so it is certainly known that chevron bones were present forward 

 of the caudals having well defined articulations. 



The anterior chevrons of No. 4934 measure 160 and 156 mm. in length, and 

 those articulated with the fourteenth and fifteenth caudals of this same series 

 measure, respectively, 119 and 109 mm. in length. 



